Enero

The Very Long Baseline Interferometry (VLBI) technique combines radio telescopes separated by thousand of kilometers to achieve the highest spatial resolutions in all of astronomy. Motivated by the need of basic stellar parameters determinations such as distances, sizes, and masses, in the star-formation field, the first goal of this work was to obtain precise measurements of distances and proper motions of young stars in the Ophiuchus and the Serpens/Aquila regions by performing multi-epoch VLBI observations with the Very Long Baseline Array (VLBA). From our observation, we were able to further investigate the structure of the clouds, derive orbital parameters of binary systems and examine the relation between the properties of young stars, such as evolutionary stage and multiplicity, and their level of radio emission detectable on VLBI baselines. The second part of the thesis focused on the source Sgr A*, which is associated with the nearest supermassive black hole, at the Galactic Center. High angular resolutions, only attainable with VLBI at millimeter wavelengths, are needed in order to detect the smallest scales and investigate phenomena related to black hole accretion and jet launching. We initiated operations for mm-VLBI observations at the Large Millimeter Telescope and performed a 3.5-mm VLBI experiment in concert with the VLBA. Because at this short wavelength the effect of the atmosphere on interferometric visibilities becomes severe, we developed and used non-imaging methods to study the millimeter emission from Sgr A*. We determined the intrinsic shape and orientation of the source at individual epochs, and interpreted the detection of substructure in the source image as possibly introduced by the interstellar medium in the direction of the Galactic Center.
Los rayos gamma de muy alta energía (E > 100 GeV) no pueden penetrar la atmósfera de la Tierra y su detección directa en el espacio es técnicamente imposible, por lo que son necesarios detectores en tierra de gran tamaño. Los telescopios MAGIC y el observatorio HAWC son ejemplos contemporáneos de las dos principales técnicas de detección de rayos gamma de muy alta energía. En esta charla se presentará las principales diferencias entre estas técnicas con sus ventajas y desventajas además de mostrar algunos de los resultados más recientes.

Febrero

16

Computo, IRyA

Se hará un resumen de los servicios y tareas a cargo de cada uno de los miembros del personal de Cómputo del IRyA. Se especificará el protocolo para la interacción usuario-Cómputo esperada (tickets), el cual nos permite atender el mayor número de solicitudes posible dadas las limitaciones de personal y tiempo. Se mencionarán los mayores problemas que se han afrontado en el último año, así como lo que se ha hecho para intentar resolverlos.
I present evidence for the existence of a new young moving group (MG) in the Northern hemisphere -- the Pisces MG, based on optical spectroscopy and kinematic data from the Gaia TGAS catalog. Constituents of moving groups provide extremely useful tests of pre-main sequence evolution and are prime targets for direct imaging of exoplanets and circumstellar material. Whilst the majority of searches for nearby, young moving groups have focused on candidates in the Southern hemisphere, the Northern hemisphere remains relatively untapped. Motivated by the potential to find new young stars in the Northern hemisphere we compiled a list of several thousand short-period, X-ray active FGK stars (8 < V < 13) from the all-sky surveys of SuperWASP and ROSAT, respectively, and obtained follow-up optical spectroscopy for ~300 to acquire radial velocities and ages. Using Li abundance as the primary age-dating technique we identified a sub-set of young (5-200 Myr), likely-single stars and calculated their Galactic space velocities.  From this young sample, we identified 15 which are co-moving, possibly co-eval and have unique space velocities: close to the Octans-Near group, but to no other previously identified MGs. This new grouping of stars would constitute the first nearby, young MG to be discovered solely in the Northern hemisphere. Given the large velocity distribution of these co-moving objects, we contemplate that these may be part of a larger structural complex, perhaps similar to that of the Local Association. In this talk I will discuss 1) how we generated our initial target sample of potentially-young objects; 2) how we measured spectroscopic parameters; 3) the impact TGAS data has made to our analyses; 4) the potential existence of the Pisces MG and 5) prospects for future searches of young, nearby stars.

Marzo

New multi-line mapping surveys of molecular clouds (e.g., CHaMP, ThrUMMS), are enabling an unprecedented demographic analysis of the physics of entire cloud populations.  Key insights from such surveys include (but are not limited to): (1) The existence of a vast population of sub-thermally excited, massive dense clumps, the majority of which are not engaged in vigorous star formation; (2) The pressure-stabilisation of these clumps against dispersal by their overlying envelopes, implying long (several ×10^7 yr) cloud lifetimes;  (3) A new CO → H2 conversion law accounting for these numerous pc-scale, low-excitation, high-opacity and high column density clumps, suggesting the total molecular mass of clouds, from pc to kpc scales in the Milky Way, may be underestimated by a factor of 2–3, and increasing the gas depletion timescale by the same factor;  (4) A revision to the concept of large molecular clouds, including GMCs, to be structures composed of pc-scale clumps (∼75% by mass) connected by a more diffuse, large-scale envelope (∼25% by mass); and  (5) Evidence for widespread flows of molecular material, both onto and away from existing cloud structures, on timescales consistent with the long cloud lifetimes and the overall low star formation efficiency in the Milky Way.  We summarise these results and discuss implications for our understanding of star formation and the life cycle of molecular clouds.
09

Carlos Carrasco / Roberto Galván, IRyA-UNAM

17
Especial

Mario Flock, JPL NASA
Coloquio Especial

In this talk I will give an overview over my latest results to compare current observations with latest 3D radiation MHD simulations of turbulent protoplanetary disks. I will focus on the dust thermal emission in protoplanetary disks, covering the outer regions which emit in the sub/mm and the inner regions which are expected to be thermally ionized and to emit in the near infrared. In the first part of my talk I will discuss the recent works by Flock et al. 2015 and Ruge et al. 2016 which are able to explain ring formation and dust concentration at the dead-zone outer edge. In these works we show that ALMA is able to resolve these structure in the dust continuum emission. In the second part of my talk I will focus on the results of first 3D radiation non-ideal MHD simulations including the inner dust rim of protoplanetary disk (Flock et al. 2016a, Flock et al. 2016b). The results show the detailed shape of the inner rim and they compare well with observational constraints. Synthetic images of the thermal dust emission in the near infrared are presented and compared with recent interferometry observations. Finally I will draw conclusions on the results and discuss about the possibility to observe MRI activity with current telescope facilities.
28
Especial

Sac Nicté Medina, Max Planck Institute for Radio Astronomy
Coloquio Especial

En este trabajo mostramos los resultados preliminares sobre un estudio estadístico de la turbulencia en los datos del survey SEDIGISM (Structure, Excitation, and Dynamics of the Inner Galactic InterStellar Medium). Los datos fueron tomados con el telecopio APEX. Para el estudio estadístico de turbulencia aplicamos la técnica VCA: Velocity Channel Analisys (Lazarian & Pogosyan 2000) sobre los cubos de datos de la linea 13CO(2-1) de 6 nubes moleculares extraídas con el algoritmo SCIME (Colombo et al. 2015). Los espectro de potencia de las nubes muestran comportamientos similares, lo cual propone una misma escala de inyeción de energía de turbulencia (1-10 pc). Estos resultados se encuentran publicados en Schuller et al. (2017). En esta charla discutiremos los compartamientos de estos espectros y su potencial para el análisis de turbulencia en el gas molecular del medio interstellar.
30

Sergio Dzib, Max Planck Institute for Radio Astronomy

Massive stars dominate the galactic environments and the full picture on how they form has not been obtained yet. In fact, this is a hot topic in the modern astronomy. In the last few years large surveys have apported new clues and have dramatically changed our view on massive star formation. These blind surveys allow to study ALL evolutionary stages of massive star formation in an unbiased way. The GLObal view of STAR formation survey is an ambitious project that will observe the galactic plane by using interferometric VLBI, submm/FIR and VLA observations. In this talk I will focus on the Galactic plane VLA survey, where we observed simultaneously the continuum and, Methanol, Formaldehyde and Radio Recombination Lines. Also, I will talk about our recent results in the range l = 28degrees to 36degrees and the galactic center region.

Mayo

This talk presents new determinations of the stellar-to-halo mass relation (SHMR) at z = 0 − 10 that match the evolution of the galaxy stellar mass function, the SFR − M relation, and the cosmic star formation rate. We utilize a compilation of 40 observational studies, corrected for potential biases.  Using our robust determinations of halo mass assembly from the several cosmological N-body simulations and the SHMR, we infer star formation histories, merger rates, and structural properties for average galaxies. Our main findings: (1) The halo mass M50(z) above which 50% of galaxies are quenched coincides with sSFR/sMAR~1, where sSFR is the specific star formation rate and sMAR is the specific halo mass accretion rate. (2) M50 increases with redshift, presumably due to cold streams being more efficient at high redshift while virial shocks and AGN feedback become more relevant at lower redshifts. (3) The ratio sSFR/sMAR has a peak value, which occurs around Mvir ≈ 2 × 10^11Msun . (4) The stellar mass density within 1 kpc, Σ1, is a good indicator of the galactic global sSFR. (5) Galaxies are statistically quenched after they reach a maximum in Σ1, consistent with theoretical expectations of the gas compaction model; this maximum depends on redshift. (6) In-situ star formation is responsible for most galactic stellar mass growth, especially for lower-mass galaxies. (7) Galaxies grow inside out. The marked change in the slope of the size–mass relation when galaxies became quenched, from d log Reff /d log M 0.35 to 2.5, could be the result of dry minor mergers

Junio

08
En este trabajo se hablará sobre la materia oscura. Se dará una introducción donde se expondrán las evidencias de la existencia de materia oscura en el universo. Posteriormente, se introducirá el modelo teórico de materia oscura fría, así como también un candidato a materia oscura conocido en la literatura como partícula tipo axion, basado en un campo escalar con un potencial trigonométrico. Se expondrá cómo este modelo de campo escalar reproduce observables cosmológicas como las anisotropías del fondo cósmico de radiación y el espectro de potencia de materia. En particular se quiere elucidar si el potencial característico de partículas tipo axion juega algún papel crucial en la formación de estructuras a gran escala en el régimen lineal
22

Josep María Masqué, Departamento de Astronomía - UGTO

Ultra-Compact (UC)HII regions represent a very early stage of massive star formation whose structure and evolution are not yet fully understood. Interferometric observations in recent years show that some UCHII regions have associated compact sources of uncertain nature. Based on this, we started a high-resolution VLA observational campaign at several  of selected UCHII regions in order to report additional cases of compact sources embedded in UCHII regions. As a preliminar result, we find 13 compact sources associated to 9 UCHII regions. Although unveiling the nature for the newly detected sources is a work in progress, we assess some of their observational properties. According to the results, we can distinguish between two classes of compact sources. One class corresponds to sources that probably are deeply embedded in the dense ionized gas of the UCHII region. These sources are being photo-evaporated by the exciting star of the region. They may play a crucial role in the evolution of the UCHII region as the photo-evaporated material could replenish for 10^4 − 10^5 yr the expanding plasma and might provide a solution to the so-called 'lifetime' problem for these regions. The other class of compact sources is not associated with the densest ionized gas of the region. Most of these sources appear unresolved and their properties are varied. We speculate on the similarity between these sources and those of the Orion population of radio sources.
The interstellar medium (ISM) plays an important role in the evolution of galaxies, and the best way to study it is by observing emission lines from the gas itself in the far infrared (FIR). With modern telescopes we are just starting to peak into the ISM of galaxies during the Epoch of Reionization (EoR), with very surprising results. My work is to invoke supercomputing powers to establish a better understanding of such observations. After a brief recap of the past few years in high-z FIR line observations, I will present the model SÍGAME; SImulator of GAlaxy Millimeter/submillimeter Emission, my main work here at the School of Earth and Space Exploration (SESE). SÍGAME builds on the output from cosmological hydrodynamic simulations of galaxy evolution to calculate the FIR line emission from different elements at any redshift desired. As examples of the method, recent results will be shown for [CII], [OI] and [OIII] of star-forming galaxies at z~6, forming part of a paper recently submitted. We find that [CII]-SFR and [OIII]-SFR power law relations come out naturally from the simulations, and I will compare with observations available at z > 5. By adopting different assumptions, we quantify how metallicity affects the [CII]-SFR relation and through a principle component analysis (PCA) we find that the the [CII] luminosity correlates most strongly with galaxy-averaged star formation rate surface density, but that molecular gas mass fraction and metallicity are also important. Finally, I will dive into future plans with SÍGAME.

Septiembre

Las estrellas masivas son las causantes principales de dar forma y enriquecer el medio interestelar (MIE) en las galaxias que vemos. Esto lo hacen debido a la combinación de diferentes factores: vientos estelares, movimientos propios, fuertes tasas de fotones ionizantes y, finalmente, como explosiones de supernova. Todos estos factores producen cavidades en elMIE que pueden ser estudiadas con observatorios de rayos X. En esta charla presento nuestroentendimiento actual de la producción de emisión difusa en rayos X en nebulosas Wolf-Rayety las implicaciones hacia otros sistemas astrofísicos.
We discuss the mechanism of cluster formation in a numerical simulation of a molecular cloud (MC) undergoing global hierarchical collapse, focusing on how the gas motions in the parent cloud control the assembly of the cluster. The global collapse implies that the star formation rate (SFR) increases over time. The collapse is hierarchical because it consists of small-scale collapses within larger scale ones. The small-scale collapses consist of clumps that are embedded in the filaments and falling on to the large-scale collapse centres. The stars formed in the early, small-scale collapses share the infall motion of their parent clumps, so that the filaments feed both gas and stars to the massive central clump. This process leads to the presence of a few older stars in a region where new protostars are forming, and also to a self-similar structure, in which each unit is composed of smaller scale subunits that approach each other and may merge. Because the older stars formed in the filaments share the infall motion of the gas on to the central clump, they tend to have larger velocities and to be distributed over larger areas than the younger stars formed in the central clump. Finally, massive stars only form once the local SFR is large enough to sample the IMF up to high masses. In combination with the increase of the SFR, this implies that massive stars tend to appear late in the evolution of the MC, and only in the central massive clumps. We discuss the correspondence of these features with observed properties of young stellar clusters, finding very good qualitative agreement.

Octubre

05

Ángeles Perez Villegas, Max-Planck-Institut für extraterrestrische Physik

Comparing data on the kinematics of the Solar neighborhood from TGAS Gaia DR1 to newly constructed made-to-measure dynamical models of the Milky Way we propose a novel explanation for the Hercules stream consistent with recent measurements of the extent and pattern speed of the Galactic bar. The model matches the 3D density of the Red Clump Giant stars (RCGs) in the bulge and bar as well as stellar kinematics in the inner Galaxy, with a pattern speed of 39 km/s/kpc. Cross-matching this model with TGAS Gaia DR1 data combined with RAVE and LAMOST radial velocities, we find that the model naturally predicts a bimodality in the U-V-velocity distribution for nearby stars which is in good agreement with the Hercules stream. In the model, the Hercules stream is made of stars orbiting the Lagrange points of the bar which moves outwards from the bar's corotation radius to visit the Solar neighborhood. This new picture of the Hercules stream naturally predicts that the Hercules stream is more prominent inwards from the Sun and nearly absent only a few 100 pc outwards of the Sun, and plausibly explains that Hercules is prominent in old and metal-rich stars.
Studying the ionization sources, dynamics of the ionized gas and the interplay between it and other phases of the ISM and the stellar populations in local galaxies is essential to understand their formation and evolution. Integral field spectroscpy (IFS) is a tool that lets us study ionized gas in local galaxies with unprecedented detail. I would like to share several projects that I am involved with that make use of IFS to study different aspects of the ionized gas: the relation between nitrogen abundance (N/O) and the stellar population content of star-forming galaxies from the CALIFA survey; the locality of the effect of close interactions in the star formation of CALIFA galaxies; the presence and significance of ionized gas in early-type galaxies from MUSE data; the interplay between AGN outflows and winds and the ISM of disk galaxies from CALIFA and MUSE data, and the effect of direct, face-on collissions in the star formation and dynamics of a sample of ring galaxies from Calar Alto / CALIFA and MUSE data. All these projects contribute to the understanding of the sources and dynamics of ionized gas and its role on the evolution of galaxies in the local universe.
The so--called jellyfish galaxies are objects exhibiting disturbed morphology, mostly in the form of tails of gas stripped from the main body of the galaxy. Several works have strongly suggested ram pressure stripping to be the mechanism driving this phenomenon. GAs Stripping Phenomena in galaxies (GASP) with MUSE is an ESO large program awarded 120 hours of time with the IFU MUSE to observe galaxies with evidences of gas stripping. I will present the goal and characteristics of the survey, and show some of the first results now that 80% of the targets have been observed.

Noviembre

Planetary nebulae (PNe) are one of the last phases in the evolution of low/intermediate mass stars (< 8 Msun), characterized by extended diffuse ionized and neutral gas surrounding the dying hot cores. Their immediate precursors are stars in the asymptotic giant branch (AGB), characterized by a strong mass-loss, followed by a short (100-10000 yr) transitional post-AGB phase. While the morphology of the mass-loss in the AGB phase is usually spherically symmetric, PNe show complex bipolar/multipolar structures. A few post-AGB stars, the water fountains (WFs), may represent the first manifestation of collimated mass-loss in evolved stars. These sources are characterized by collimated jets traced by high-velocity water masers. The study of WFs and very young PNe is crucial to understand the variety in the morphology shown by PNe. Through polarimetric observations of maser-emitting PNe and WFs is possible to have a detailed picture of the magnetic field (structure and strength) associated with these sources. Magnetic fields are a key ingredient in the early evolution and shaping process of PNe, as well as in the stellar mass-loss. Radio continuum observations provide information about emission processes (thermal/non-thermal) associated with WFs and PNe. In this talk, I will present our recent results on polarimetric observations toward maser-emitting PNe.
16

Roberto Terlevich, INAOE, Mexico / IoA, Cambridge, UK

Informaré los ultimos resultados utilizando el estimador de distancia L(Hbeta)-sigma basado en la correlación entre las dispersiones de velocidad de gas ionizado y la luminosidad de la línea de emisión de Balmer de las galaxias HII y regiones HII gigantes para trazar la expansión del Universo a z < 3.5 con instrumentacion presente y en el futuro a z ~ 6-7 con el JWST. Este enfoque proporciona restricciones independientes sobre H0, Ωm y la ecuación de estado de la energía oscura w y de su posible evolucion en corrimientos al rojo que no son alcanzables con otros metodos (SNIa,BAO y CMB). Con respecto a H0, hemos recalibrado la muestra de anclaje de las regiones de HII gigantes en galaxias cercanas con distancias determinadas con métodos primarios vía Cefeidas y TRGB. El valor de H0 que obtenemos es intermedio obtenido por Riess et al 2016 utilizando SNIa y el resultado de la colaboracion Plank. Con respecto a Ωm y w, el uso de espectroscopia de alta dispersión Visible-NIR de galaxias HII con desplazamientos al rojo entre 0,6 y 2,7, obtenido en el VLT utilizando XShooter más algunas galaxias HII de alto z de la literatura mejora las restricciones y destaca la necesidad de perfiles de línea de emisión de alta calidad. También discutiré simulaciones basadas en estos primeros resultados que muestran que restricciones altamente competitivas a Ωm y w se pueden obtener utilizando una muestra de 500 galaxias HII de alto desplazamiento al rojo con datos de alta calidad que se pueden obtener con instrumentos como KMOS en el VLT o MOSFIRE en KECK en unas 25 a 50 noches. Nuestros ultimos datos obtenidos con MOSFIRE en KECK confirman las simulaciones y dan resultados en el plano Ωm - w de similar calidad a los que Amanullah etal 2010 obtienen utilizando la compilacion Union2 de 557 SNIa.
23

Academia Mexiacana de Ciencias,
Próximo Coloquio

30

Rosa Amelia Gonzalez Lopez-LIra,

Diciembre

La gran mayoría de las estrellas se forman en cúmulos. En la presente charla presentaré resultados de simulaciones numéricas de núcleos densos masivos de nubes moleculares, mostrando: (a) cómo el colapso jerárquico y caótico de nubes masivas produce una pendiente en la función de masa inicial con pendiente de -1 de manera natural, hecho que sugiere fuertemente que la acreción es de tipo Bondi-Hoyle. (b) cómo las regiones con mayor curvatura producen que el material se apile, y los cúmulos masivos se forman a partir de la fusión de cúmulos más pequeños; (c) cómo la evolución del potencial tanto estelar como del gas es importante para la coalescencia de los cúmulos. (d) cómo el análisis de inestabilidad gravitacional, tanto de un core, como de un filamento., puede dar conclusiones erróneas sobre el estado dinámico de los cúmulos. Nuestros resultados son consistentes con una serie de características observacionales reportadas recientemente tanto en gas como en estrellas en cúmulos como el de la nebulosa de Orión.

Enero

Many luminous Early Type Galaxies (ETGs; M_B < -20.5 mag) are characterized by depleted stellar cores, i.e. marked flattenings of the inner light distribution relative to the outer profile of the ETG spheroid.The structural characteristics of cores clearly depend on the formation history of the ETG, and in the last decades they have been shown to correlate with the mass of the central Super-Massive Black Hole (SMBH). This addresses to a link between the formation of the SMBH and that of the core.It has been suggested that Black Hole (BH) binaries, established during dry (i.e. gas-poor) mergers which shaped the ETG, kick stars out of the galaxian nucleus via three-body interaction, before coalescing into the central SMBH.In this talk, this "binary BH scouring scenario" is tested at its extremes by investigating the galaxies with the alleged largest cores found in the Local Universe; alternative core formation scenarios are promoted.
21

Mariana Vargas Magaña, IF-UNAM

Cosmic acceleration is one of the most important issues to be explored by modern observational cosmology. Cosmic acceleration can be explained by either modifying General Relativity on cosmological scales, or within the framework of the standard cosmological model this implies that ~70 per cent of the Universe is dominated by a new component called “dark energy” with the unusual physical property that opposes the attractive force of gravity. I will present the results of the Baryon Oscillation spectroscopic Survey (BOSS) that uses the baryon Acoustic Oscillation to extract information about the equation of state of dark energy. The BAO feature corresponds to the maximum distance travelled by acoustic waves in the matter-radiation fluid during the period from matter/radiation equality to their decoupling at z~1100 and then stretched by expansion of universe. This feature can be seen as a standard ruler allowing us to study the history of the expansion of the Universe and infer cosmological information. I will present the latest cosmological constraints in dark energy and extensions of LCDM that we can extract combining BAO with the cosmic microwave background (CMB) data and Type Ia supernova (SN) data.
26
Especial

Johannes Schmid-Burgk, Max Planck Institute for Radioastronomy
Coloquio Especial

28

Isabel Tatiana Rodrguez E., U. de Guanajuato

Hypercompact HII regions are ionized gas regions associated with the earliest stages of high-mass star formation. These regions are characterized by their small sizes (􏰁smaller than 0.05 pc), high electron densities (larger than 1e6 cm^−3) and emission measures exceeding 1e9 pc/cm^6. Unlike ultracompact HII regions, which typically host a cluster of massive stars, hypercompact (HC) HII regions are thought to surround a single star or perhaps a binary system. As such, HC HII regions present us with a laboratory to study the physical processes involved in the formation of single stars, without the complicating phenomena of a cluster environment.In this work, we study five candidate HC HII regions originally observed at 1.3 and 3.6 cm. These regions were selected because they show 6.7 GHz methanol maser emission ( a tracer of high mass star formation) but they show little or no emission at 6 and 20 cm (indicating a pre-ultracompact HII region stage). All sources show extended 8 and 24 micron emission further supporting their identification as very young high-mass star-forming regions.To confirm the classification and to understand better the nature of these regions, we made observations at 2 and 6 cm, using the Jansky Very Large Array (JVLA) with an angular resolution of about 2 arcsec. Here we report our detections, showing the radio images and the measured parameters.We present a preliminary analysis of our results, including the modeling of the spectra as uniform and non-uniform spheres.

Febrero

We present our study on the evolution of galaxy properties in compact groups over the past 3 Gyr. We are using the largest multi-wavelength sample to-date, comprised of 1770 groups (containing 7417 galaxies), in the redshift range of 0.01<z<0.23. To derive the physical properties of the galaxies we rely on ultraviolet (UV)-to-infrared spectral energy distribution modeling, using CIGALE. We find a significant increase of the number of the AGN-hosting galaxies as we are moving towards lower redshifts, and we report the absence of Seyfert 1 nuclei. We also show that at any given stellar mass, galaxies in dynamically old groups are more likely to host an AGN. Our results also suggest that during the 3 Gyr period covered by our sample, the star formation activity of galaxies in our groups has been substantially reduced (3-10 times). Moreover, their observed UV-optical and mid-infrared colours are consistent with star formation rate histories, which are significantly different from those of galaxies in the field and in clusters, as the former spend more time tran- sitioning through the green valley. We also find evidence that the morphological transformation of late-type galaxies into earlier types, occurs during the mid-infrared green valley transition rather than during the UV-optical one. Examining the emission line ratios and gas velocity dispersions of the late-type galaxies located below the star forming main sequence, we find evidence of shocks.
9
Especial
Stellar masses of galaxies are frequently obtained via SPS fitting to observed photometry, or galaxy spectra. "State of the art" methods resolve spatial structures within a galaxy to asses the total stellar mass content. In comparison to unresolved studies, resolved methods yield higher fractions of stellar mass for galaxies. In this talk we will demonstrate that current methods commonly deliver biased resolved spatial structures. We will discuss the cause of this bias, an introduce a new method, based on Bayesian statistics, aimed to mitigate the bias. We applied this method to M51, and a pilot sample of spiral galaxies. We will compare quantitatively the application of both methods and discuss the results.
11

Breno Loureiro Giacchini, Centro Brasileiro de Pesquisas Físicas

El registro de ocultaciones estelares es la mejor técnica desde el suelo para determinar parámetros físicos de cuerpos distantes en el Sistema Solar, tales como tamaño y forma, con precisión de pocos kilómetros. Además, permite el estudio del ambiente cercano al objeto, verificando la presencia de anillos, satélites y atmósferas tan débiles cuanto algunos nanobars. Nuestra charla se concentrará en ocultaciones de estrellas por la Luna, por asteroides y por objetos transneptunianos. En la primera parte de esta charla trataremos de las particularidades y la importancia de observar cada uno de esos tres tipos de ocultaciones. Luego presentaremos algunos resultados obtenidos en Brasil en los últimos años, como en los eventos producidos por el asteroide (52) Europa (agosto de 2012), el centauro (10199) Chariklo (junio de 2013) y el planeta enano (1) Ceres (agosto de 2010 y octubre de 2013).
25

Xavier Hernández Doring, IA-UNAM

Repasare las motivaciones astrofisicas detras de la hipotesis de la Materia Obscura, y hablare sobre el estado actual del campo. A pesar de decadas de esfuerzos dedicados, a la fecha no hay una sola deteccion de este componente, hipoteticamente dominante. Describire desarrollos recientes que indican cambios a la ley de gravedad a escalas astrofisicas, consistentes con propuestas de gravedad modificada construidas explicitamente para explicar las observaciones astronómicas sin requerir materia obscura.

Marzo

We summarize our comprehensive gas surveys of some of the most luminous (Lbol 1e5 to 1e7 Lsun), deeply embedded (optically obscured) star formation regions in the Milky Way, which are the local cases of massive star clusters and/or associations in the making. Our approach emphasizes multi-scale, multi-resolution imaging in dust and free-free continuum, as well as in molecular- and hydrogen recombination lines, to trace the multiple gas components from < 0.1 pc (core scale) all the way up to the scales of the entire giant molecular cloud (GMC), or ~ 100 pc. We highlight our results on W49A, the most luminous Galactic star formation region (Lbol ~ 2e7 Lsun), which appears to be forming a young star cluster (or a binary star cluster) with M_star ~ 1e5 Msun that may remain bound after gas dispersal. We also highlight our recent result on the G33.92 region (Lbol ~ 3e5 Lsun), where ALMA mapping reveals that the cluster-forming accretion flow is arranged in a fragmented spiral-like structure from clump to core scales. Preliminary results in a handful of other regions will be shown.
10

Juana Leticia Rivera, IRyA-UNAM

El Cinturón de Gould es una de las estructuras más interesantes de nuestra galaxia, con sus ~ 10 ^ 6 masas solares de gas y estrellas jóvenes fuera del disco y colocadas apropiadamente sobre un anillo alargado de ~ 270pc y con una inclinación de ~20º respecto del disco. El estudio de la dinámica local y la evolución de esta estructura nos puede dar una muy buena idea de la dinámica y evolución de galaxias en general y también profundizar en la teoría de la formación estelar. Utilizando los datos de archivo y VLA recientes observaciones sobre el Karl G. Jansky Very Large Array se desarrolló un código semi automatico en Python / CASA para seleccionar, reducir y analizar varias estrellas jóvenes pertenecientes al núcleo de Ofiuco y nube molecular de Tauro. Este código está hecho para ayudar a seleccionar las observaciones realizadas a lo largo de los más de 30 años de servicio del VLA hechas en las regiones de formación de estelar mencionadas con las configuraciones de ancho A y B, que nos dan una mejor resolución y en las bandas X y C, donde estos objetos estelares jóvenes son más brillantes, para determinar su posición y compararla con las más recientes y de esta manera es posible determinar su movimiento propio con una precisión muy alta. Se presentan los resultados de las estrellas centrales: S1, DOAR 21, VLA1623 y YLW15 de Ofiuco, también con los resultados en las velocidades radiales, ya publicadas junto con los nuevos resultados de estrellas en la nube molecular de Tauro que es otra importante región de reciente formación estelar que pertenece a la Cinturón de Gould. Hay dos principales teorías sobre el origen Cinturón de Gould uno describe un evento catastrófico que involucró a varias supernovas, el cálculo de la energía sugieren 20 supernovas hace 30 millones de años. Este evento provocó que el gas y el polvo escaparan lejos del disco y algunos años después comenzó la formación estelar y formaron los rasgos característicos que reconocemos ahora. La segunda teoría habla sobre el impacto de una nube compacta de alta velocidad contra el disco galáctico, este impacto sacó el polvo y gas del disco dejándolo a ~20º tal como el Cinturón de Gould se muestra ahora. Ambas teorías serían distinguibles debido a las diferencias en sus movimientos propios absolutos y velocidades radiales. Estamos cerca de discernir cuál es la teoría más adecuada del origen Cinturón de Gould de entre estas últimas, teniendo en cuenta la dinámica del núcleo de Ofiuco y la región de la nube molecular de Tauro
29
Especial

Miguel Alcubierre, ICN - UNAM
Coloquio Especial

La teoría de la relatividad general fue postulada por Albert Einstein a fines de 1915. Una de sus principales predicciones son las ondas gravitacionales, perturbaciones en el espacio-tiempo que viajan a la velocidad de la luz y que se son producidas por fenómenos astrofísicos violentos, como explosiones de supernovas o colisiones de agujeros negros. Sin embargo, las ondas gravitacionales son tan débiles que tomó mas de 100 años detectarlas. En esta charla daré una breve introducción al concepto de las ondas gravitacionales, así como los emocionantes resultados relacionados con su primera detección, anunciada en febrero de 2016.

Abril

7

Alberto Carramiñana, INAOE

HAWC es un observatorio de rayos gamma de gran campo de visión (1.8sr) y ciclo de operación (>95%) de capacidades únicas para el estudio de fuentes celestes de fotones de altas energías (> 100 GeV). HAWC está ubicado en la ladera norte del volcán Sierra Negra a 4100m, un kilómetro al norte del Gran Telescopio Milimétrico Alfonso Serrano con el cual comparte la infraestructura básica. Inaugurado en marzo de 2015, después de un año y medio de operaciones científicas con 1/3 del arreglo de detectores instalado, HAWC observa diariamente 2/3 de la bóveda celeste, detectando la nebulosa del Cangrejo en cada tránsito, monitoreando galaxias activas y escudriñando el Plano Galáctico.
We have performed a selection of intermediate mass stars (spectral types F5 or earlier) candidates that potentially exhibit protoplanetary disks based on infrared data from the 2MASS and WISE catalogs. Of particular interest are Herbig Ae/Be stars, which exhibit near infrared excesses produced in the inner wall located at the dust destruction radius and emission lines produced by accretion mechanisms. The area surveyed is ~1000 square degrees and includes the Orion OB stellar associations. Distances normally assumed for young stars located in this region range from 300 pc to 500 pc. We have initiated optical spectroscopic follow-up observations of selected candidates using the spectrographs OSU-CCDS at the observatory MDM and the Boller & Chivens at the observatory San Pedro Martir. Our main goal is to build a large scale census of protoplanetary disks around intermediate mass stars that will contribute to a better understanding of the star forming and disk evolution processes, as well as possible relationships between the environment and the spatial distribution of stars in this mass regime.
18
Especial

Stephane Courteau, Queen's University
Coloquio Especial

Galaxies like our Milky Way can be described in terms of their structure, dynamics, and stellar populations. Some very robust correlations between galaxy structural properties, such as total luminosity, maximum circular velocity, and size show rather small scatter, hinting at well-regulated galaxy formation processes. A major challenge to understanding these scaling relations, and ultimately galaxy formation and evolution, is the elusive interplay between visible and dark matter. I will discuss the latest constraints to galaxy scaling relations and their link with modern cosmological models.
28
All massive galaxies harbor a supermassive black hole in their centers. A phase during which the central black hole accretes the surrounding matter and grows considerably is referred to as the Active Galactic Nucleus (AGN). The strong radiation from the gas spiraling into a black hole is partially reprocessed by the dust clouds placed further out in a roughly toroidal shape ("the dusty torus") and is released in the infrared. Thus, the ratio of the AGN and torus luminosities (L_AGN/L_tor) is commonly used as the dust covering factor (CF) proxy. Using state-of-the-art Monte Carlo radiative transfer code, we critically investigated the relation between the L_AGN/L_tor and the CF. We found that in most of the cases L_AGN/L_tor significantly over- or underestimates the true CF. Our results provide a new straightforward way to account for the effects leading to this and obtain true CFs. We demonstrate the importance of these results for inferring the obscured fraction of AGNs as a function of L_AGN by applying the corrections to the two large samples from the literature, showing that CF has much weaker dependence on L_AGN than previously thought. Our results suggest a higher fraction of obscured AGNs at high luminosities than those found by X-ray surveys, partially due to the presence of a Compton-thick AGN population, which is missed by X-ray surveys, but not by infrared.

Mayo

5

Nahiely Flores Fajardo, Foro Consultivo Científico y Tecnológico

Un problema persistente en la astrofísica nebular es la determinación de las abundancias químicas de una nebulosa fotoionizada, principalmente porque se requieren determinaciones precisas de la densidad (Ne) y la temperatura electrónicas (Te). También existe el problema de que la determinación de las abundancias químicas mediante diferentes métodos empíricos arroja diferentes resultados. Una manera de solventar este problema es confrontando las observaciones con las predicciones de modelos teóricos, en particular de fotoionización. Aunado a ello, desde los años 90 se observaron, dentro de las Nebulosas Planetarias, estructuras bipolares cuya emisión en [N II] era mucho más fuerte que el resto de la nebulosa (FLIER, Fast Low Ionization Emission Region). Desde entonces existe una discrepancia en la determinación de las abundancias químicas de estas estructuras, y por lo tanto, del escenario de su formación y evolución. En este trabajo se presenta la determinación de abundancias de la Nebulosa Planetaria NGC6826 y del FLIER NW a partir de la confrontación de observaciones de espectroscopía óptica con modelos autoconcistentes 1D de fotoionización tomando en cuenta tres escenarios diferentes de evolución de los FLIERS.   
One of the most exciting and unsolved problems in Astrophysics is figuring out the origin of the Ultra High Energy Cosmic Rays. These are particles having an energy of about 100 EeV (which is a billion times the energy of the Higgs boson) and arrive on the Earth from outside the Galaxy, but their origin remains unknown. It has been suggested that relativistic shocks in extragalactic sources like Active Galactic Nuclei may accelerate the highest energy cosmic rays. The maximum energy to which cosmic rays can be accelerated depends on the structure of magnetic turbulence near the shock but recent theoretical advances indicate that relativistic shocks are probably unable to accelerate particles to energies much larger than 1 PeV. We study the hotspots of powerful radiogalaxies, where electrons accelerated at the termination shock emit synchrotron radiation. The cut-off of the synchrotron spectrum is typically observed between infrared and optical frequencies, indicating that the maximum energy of non-thermal electrons accelerated at the shock is about 1 TeV for a canonical magnetic field of 100 micro Gauss. Based on theoretical considerations we show that this maximum energy cannot be constrained by synchrotron losses as usually assumed, unless the jet density is unreasonable large. We test this result by considering a sample of hotspots observed with high spatial resolution at radio, infrared and optical wavelengths.
19

Alex Binks, IRyA

Despite many decades of theoretical effort and large volumes of high-precisionobservations, obtaining ages for stars accurate to within ~10% remains a difficult and often elusive challenge for stellar astrophysics. In constrast, cosmologists can claim a precision of 1% for the age of the Universe! In this talk I provide a general overview of the various techniques at our disposal to estimate the ages of young, nearby stars. I will adopt a hierarchial approach in this review, in order of decreasing precision and/or utility. Firstly I will examine "semi-fundamental" techniques that rely on well-understood physics - the lithium depletion boundary method and kinematic tracebacks. Next I will discuss the "model-dependent" methods that are subject to various inputs in the stellar physics - the isochronal method, upper main-sequence fitting and asteroseismology. Finally I will describe the "empirical" methods, which rely on, at their very least, a non-monotonic age-functional form that is often poorly constrained - rotation, activity and lithium in FGK stars. In my summary I provide a forecast for future stellar chronometry, focusing on the prospects expected from the GAIA mission which should provide micro-arcsecond precision astrometry (due for first data release in Summer 2016).
Presentaré las principales características del Plan de estudios de la Maestría y el Doctorado en Astrofísica que se implantará en el semestre 2017-1 (agosto-diciembre 2016). Hare incapie en las modificaciones mas relevantes de ambos planes de estudios: 1) Maestria: requisitos de ingreso y modalidades de graduación. 2) Doctorado: Requisitos de ingreso.
30
Especial

Grainne Costigan, Universidad de Leiden
Coloquio Especial

The Gaia mission will provide us with an unprecedented stereoscopic map of the heavens and will likely be the astronomical data resource for decades thereafter, representing a tremendous discovery potential. It will measure parallaxes and proper motions for every object in the sky brighter than magnitude 20 - amounting to 1 billion stars, galaxies, quasars and solar system objects. I will summarise the Gaia mission, performance so far and some early discoveries. The complexities of the final Gaia catalogue, and the science we want to extract from it, will force us to be very ambitious in the way we publish the Gaia catalogue. In order to unlock the full potential, we need to integrate the Gaia catalogue with other sky surveys and provide advanced statistical approaches and visualisation tools to allow the community to explore the data, do the science they expect and to facilitate the discovery of the unexpected. I will mention some of the efforts that are being undertaken within the scientific community to tackle these aspects and how these along with the Gaia data will be made available.

Junio

9

Adal Mesa Delgado, Pontificia Universidad Católica de Chile

Ring nebulae are interstellar bubbles of ionized gas that have swept-up the surrounding interstellar medium after the mass loss episodes experienced by their massive progenitors, especially during the Wolf-Rayet phase. The presence of stellar ejecta in ring nebulae allows us to better understand the nucleosynthesis of massive stars and the effects of the H-burning reactions on the elements involved in the CNO cycle. A detailed analysis of the chemical composition and abundance ratios of these elements provides us valuable information to constrain stellar evolution models of massive stars and the evolutive scenario of the stellar progenitors. Within this framework, we will present results from new spectroscopic data in the optical range of the Galactic ring nebulae NGC6888, G2.4+1.4,  RCW58 and NGC7635 based on very deep observations obtained with the 10m GTC telescope and the 6.5m Clay telescope. In comparison with previous studies, these new observations have allowed us to derive physical conditions and chemical abundances with great accuracy in different zones of the nebulae. Therefore, we have been able to detect and localize areas of shocked gas, and investigate the presence of chemical inhomogeneities in these objects. Additionally, we will present the first determinations of C abundances in these ring nebulae based on the faint recombination line CII 4267 A as well as their implications when comparing with the predictions of stellar evolution models. These crucial results represent the first constrains on C abundances, providing long-awaited information on the action of the CNO cycle that controls the nucleosynthesis processes in massive stars.
16

Varios, IRyA

Spectroscopy, as a tool, has permitted some of the most fundamental discoveries in the study of the Milky Way. With the growing number of Galactic surveys (e.g. the Gaia-ESO survey, GALAH, APOGEE) in medium and high resolution, the number of stars observed will amount to several hundred thousands in the near future requiring precise analyses of their spectra in terms of their atmospheric parameters and chemical abundances. In this talk, I will present the main spectroscopic methods for the derivation of the stellar atmospheric parameters (namely the effective temperature, surface gravity, metallicity) and the fields where stellar characterization plays a key role. In particular, these tools enable us to distinguish and define the different stellar populations our Galaxy is composed of. I will also describe why this work comes in good time for the analysis of the Gaia data, a very anticipated mission for the study of our Galaxy.
30

Esteban Silva-Villa, Universidad de Antioquia

For decades we have understood the star clusters as a bound association of stars that share their age and their metallicity. This was due to the understading that stars inside a star clusters formed from the same mother cloud. However, during the past ~10 years new observations have been challenging this idea. Multiple stellar populations have been observed inside particular star clusters, where stars with different metallicities have formed in large numbers inside clusters. In this seminar, I will present the background of this open problem in the field and the possible solutions to this problem.

Agosto

1
Especial


Coloquio Especial

4
During the last 30 years spectral studies of the broad iron K-alpha line and the Compton hump in the X-ray spectra of AGN have shown that the X-ray source illuminates the innermost part of the accretion disc in these systems. Further support to this hypothesis is provided by the detection of delays between the X-ray continuum variations and the spectral features that are supposed to be produced by X-ray reflection (mainly the soft-excess and the iron line). The X-ray reprocessing by the disc should also affect the X-ray continuum variability properties. The observed X-ray power-spectra should show a prominent dip at high frequencies and an oscillatory behaviour, with a decreasing amplitude, at higher frequencies. These reverberation “echo” features should be more prominent in energy bands where the reflection component is more pronounce, and should depend mainly on the central black hole mass and the X-ray source height. The detection of the X–ray reverberation signals in the PSDs can provide further evidence for X-ray illumination of the inner disc in AGN  and can be used to map out the geometry of the inner accretion flow (which cannot be studied in any other way).
11

Miriam E. Ramos Ceja, Argelander Institute für Astronomie, Universidad de Bonn

I will present forecasts on galaxy cluster counts from the X-ray survey with the future eROSITA mission. Clusters of galaxies are the largest gravitationally-bound objects in the Universe. Thereby clusters are ideal tracers of cosmic expansion and structure formation that allow tight constraints on the average cosmic density of matter and of other fundamental cosmological parameters. In this talk I will show how we study the detection efficiency of galaxy clusters of the upcoming eROSITA X-ray mission. The cluster detection probability is investigated by means of extensive and dedicated Monte Carlo simulations, and employing a state-of-the-art source detection technique we determine a cluster detection eefficiency based on the cluster fluxes and sizes. Using this eROSITA cluster selection function, we found that eROSITA will be able to detect a total of  1.36x10^5 clusters in the whole sky. This cluster number will allow eROSITA to put stringent constraints on the dark matter and dark energy models.
Potentially habitable planets within the habitable zone of M-dwarfs are affected by tidal interaction. We studied the tidal evolution in GJ 667C using a numerical code we call TIDEV. We reviewed the problem of the dynamical evolution focusing on the effects that a rheological treatment, different compositions and the inclusion of orbital perturbations, have on the spin-down time and the probability to be trapped in a low spin-orbit resonance. Composition have a noticiable effect on the spin-down time, changing, in some cases, by almost a factor of 2 with respect to the value estimated for a reference Earth-like model. We calculated the time to reach a low resonance value (3:2) for the configuration of 6 planets. Capture probabilities are affected when assuming different compositions and eccentricities variations. We chose planets b and c to evaluate the probabilities of capture in resonances below 5:2 for two compositions: Earth-like and Waterworld planets. We found that perturbations, although having a secular effect on eccentricities, have a low impact on capture probabilities and nothing on spin-down times. The implications of the eccentricity variations and actual habitability of the GJ 667C system are discussed.
En este seminario hablaré del trabajo que presenté para mi tesis de licenciatura en la Universidad Autónoma de Barcelona para obtener los títulos de Graduado en Física y Graduado en Química. El trabajo consta de una parte dedicada a la Radioastronomía y otra parte dedicada a la Química Cuántica. En la primera parte, presentaré observaciones de líneas moleculares de 26 regiones de formación estelar de alta masa, que cubren diferentes estados evolutivos. Dichos espectros fueron tomados con el radiotelescopio IRAM-30m y cubren una banda de 16 GHz. Mostraré los ajustes de los espectros hechos con XCLASS para obtener los parámetros físicos de las regiones, y daré una primera idea de la química que caracteriza cada estado evolutivo. En cuanto al trabajo de química, presentaré las herramientas computacionales químico-cuánticas que he usado para diseñar la formación del CH3CHO usando dos modelos de reactividad, ambos tanto sobre superficies de hielos de agua como en fase gas. Finalmente, relacionaré las conclusiones de los modelos químico-cuánticos con los resultados observacionales presentados en la primera parte.

Septiembre

1

Joel Sánchez Bermúdez, Max Planck Institute for Astronomy (MPIA)

During the last decade, the use of optical/infrared interferometry has grown up to study stellar physics. Facilities like the Very Large Telescope Interferometer (VLTI) in Europe, or the CHARA array in the United States have proven to play a key role to perform high-angular resolution observations. The scientific cases addressed with this technique go from the study of (massive) young stellar objects to multiple systems or evolved stars. In this talk, I will perform a review of the basic principles of the optical/near-infrared interferometry and of the current European facilities to use this observational technique. Particularly, I will describe the main differences between radio and infrared interferometry (e.g., the observables and the problem of image reconstruction). I will provide a review of the current (and future) instruments available at the ESO VLTI, enhancing their advantages and limitations. Finally, as a show case, I will present my current studies of massive stars using this technique, paying special attention to the characterisation of multiple systems and of the winds of the massive stars at the Galactic Center.
We test the predictions of spectral synthesis models based on seven different massive-star prescriptions against Legacy ExtraGalactic UV Survey (LEGUS) observations of eight young massive clusters in two local galaxies, NGC 1566 and NGC 5253, chosen because predictions of all seven models are available at the published galactic metallicities. The high angular resolution, extensive cluster inventory, and full near-ultraviolet to near-infrared photometric coverage make the LEGUS data set excellent for this study. We account for both stellar and nebular emission in the models and try two different prescriptions for attenuation by dust. From Bayesian fits of model libraries to the observations, we find remarkably low dispersion in the median E(B - V) (~0.03 mag), stellar masses (~10^4 M⊙), and ages (~1 Myr) derived for individual clusters using different models, although maximum discrepancies in these quantities can reach 0.09 mag and factors of 2.8 and 2.5, respectively. This is for ranges in median properties of 0.05-0.54 mag, 1.8-10 × 10^4 M⊙, and 1.6-40 Myr spanned by the clusters in our sample. In terms of best fit, the observations are slightly better reproduced by models with interacting binaries and least well reproduced by models with single rotating stars. Our study provides a first quantitative estimate of the accuracies and uncertainties of the most recent spectral synthesis models of young stellar populations, demonstrates the good progress of models in fitting high-quality observations, and highlights the needs for a larger cluster sample and more extensive tests of the model parameter space.
22

Enrique Vázquez, IRyA-UNAM

I review the evolution of our understanding on the nature, structure and dynamics of molecular clouds (MCs). I start with the first observations of molecular and the quick realization that they imply supersonic motions in MCs, which initially were interpreted as gravitational collapse. However, it was soon argued that global collapse of the clouds would imply a SFR larger than observed by two orders of magnitude. Then it was proposed that MCs were supported against collapse by some agent causing them to survive for much longer times than their free-fall times. I then review the two main paradigms of cloud support: magnetic and turbulent, discussing their basic features, and the reasons leading to their demise. Finally, I discuss the evidence that in the last half-decade has suggested a return to the global collapse scenario, and how the SFR is regulated in this case.
29

Jesus A. Toala, Academia Sinica

Born-again planetary nebulae (PNe) represent unique objects in the evolution of thecircumstellar medium around low-mass stars (M < 8 Msun). The central starsof these PNe are thought to have experienced a very late thermal pulse when they were in the white dwarf track that produced the ejection of newly processed material inside the old PN. This scenario offers the opportunity to study the wind-wind interaction and production and destruction of molecules and dust in human scales (~20-100 yr). In this talk I present a review of our multi-wavelength campaign to characterise bona-fide born-again PNe using ground-based telescopes and satellites.

Octubre

Despite much effort has been devoted to characterize the dusty tori in active galactic nuclei (AGN), very little is still known in those with high bolometric luminosity, mostly quasi-stellar objects (QSOs). This is mainly due to their compactness and sparseness in the local Universe. Mid-IR high angular resolution observations offer a good oportunity to step foward in their understainding. In this talk, I going to present new high angular resolution mid-IR data (0.3 arcsec)  obtained with the IR camera CanariCam (CC) on the 10.4m Gran Telescopio CANARIAS, for a sample of 20 nearby QSOs. The analysis  of the images at Si2 band (8.7 um) reveals that the mid-IR emission is unresolved in the majority of QSO at scales < 600 pc. We compare the IRS/Spitzer  and the ground-based CC spectra and find that the spectral shapes are similar, and hence adopt the former to isolate the AGN component. We find that on average the AGN contributes 85 per cent of the total mid-IR emission within the IRS/Spitzer apertures (~3.5 arcsec), while the rest can be atribbuted to  starburst emission. We use unresolved near-IR emission from the literature and the starburst-subtracted mid-IR spectra to constrain the physical and geometrical parameters of clumpy dusty torus models of Nenkova et al. We find that for most QSOs the unresolved SED and spectroscopy can be well reproduced  by the models without the inclussion of a hot dust component, as propose in the literature. Finally, a statistical comparison between  the parameters of the dusty torus of QSOs derived by us and the dusty torus of some Seyfert 1s and 2s studied with a similar technique for others authors, shows that the properties of the dusty torus in QSOs are intrinsically different from those of Seyfert 1 and 2 nuclei. Nevertheles, in QSOs the parameters derived (e.g., the covering factor) are consistent with the optical classification of QSOs as type 1 AGN.  An analysis on the dependence of the covering with the bolometric luminosity suggests that these differences can be attributed to dusty structures that have been partly evaporated and piled up by the higher intensity radiation field in QSOs, as proposed by a receding torus scenario.
Uno de los objetivos que tiene la misión EUCLID es el estudio de la naturaleza de la energía oscura, para lograr esto es necesario contar con métodos que nos permitan realizar un análisis lo más general posible. Uno de los marcadores más claros que distinguen LCDM de modelos alternativos es lo que se conoce como el estrés anisotrópico η = −Φ/Ψ. En esta plática presentaré las constricciones actuales y futuras para este marcador usando un método que es independiente tanto del modelo como de la evolución cósmica en el rango de observación y del bias. Por otro lado construiremos una gráfica de exclusión, similar a las utilizadas en experimentos de gravedad hechos en laboratorio, con base en el pronóstico de observaciones bajo las especificaciones de EUCLID y adoptando una forma general de η que abarca todas las teorías dentro de la formulación de Horndesky, encontraremos así qué tan bien las mediciones futuras de agrupamiento de galaxias, de H y de lente débil podrían constreñir su valor tomando como modelo de referencia LCDM. Finalmente mostraremos cómo extender este método cuando utilizamos un modelo de referencia alternativo, en particular f(R).
The relevance of galaxy bulges as central pieces in the study of galaxy formation is nowadays well settled. Bulges come in two flavours: classical and disk-like bulges. Different formation mechanisms have been proposed to explain this dichotomy and therefore understanding their demography is of vital importance to unveil galaxy formation. In this talk, I will present the results of a careful photometric analysis of the galaxies present in the CALIFA survey. Using the available SDSS photometry, we found a zoo of morphological structures (single and double bars, broken exponential profiles, etc), with bulges following this diversity in terms of a wide range of masses and concentrations (i.e., Sersic index). In particular, I will focus on the observed properties of bulges in lenticular galaxies where, by definition, they are suppose to play an important role in their evolution. Combining the photometric analysis of the galaxy bulges with the stellar kinematic information about their rotational support (angular momentum), we suggest that lenticular bulges were mainly formed through dissipational processes at high redshift, either wet major mergers or coalesce of giant star-forming clumps. I will discuss these results in the general context of lenticular galaxies formation.

Noviembre

We are at present in an very exciting era for the study of how planets form. During the previous decades, observations with powerful radiointerferometers, specially the Very Large Array (VLA), have well established that planet formation is a natural consequence of the star formation process itself. Planets are most probably formed as dust evolve in the circumstellar disks around Young Stellar Objects (YSOs). It is now that, the extraordinary observing capabilities of the Atacama Large Millimeter Array (ALMA) are offering us an unprecedent level of detail of circumstellar disks around YSOs. The recent ALMA observations with very high angular resolutions of several disks are revealing several structures, consequences of the dust evolution, and most probably associated with the initial stages and/or ongoing planet formation. However, the contribution of the VLA to this field has not yet finished. Instead, the VLA with its recent upgrade, is still in the race and it is indeed revealing itself as a fundamental instrument to investigate the planet formation process. It seems necessary to still observe at longer millimeter wavelengths than ALMA in order to be able to penetrate very dense regions in the disks. This is specially critical at the earliest stages and at the innermost parts of the disks where, for example, terrestrial planets are expected to form. Here, I will present some very recent observations with the VLA of two very young circumstellar disks (HL Tau and HD 169142). I will also discuss how the combination of VLA and ALMA images is what actually could provide a giant step in the understanding of the planet formation process.
Se describen los censos del cielo extragaláctico trazados en ondas milimétricas con la instrumentación del Gran Telescopio Milimétrico Alfonso Serrano (GTM), que nos han permitido encontrar galaxias lejanas con brotes de formación estelar que exceden las 1000 masas solares al año en áreas de alrededor de 3 mil años-luz de diámetro. Estos extraordinarios sistemas probablemente forman estrellas en un regimen ligado por gravedad, en el que el material que eyectan las estrellas no puede formar un viento galáctico que frene la formación estelar, sino que se recicla para formar nuevas generaciones de estrellas. Se presenta la evidencia para sostener que estas galaxias son probablemente los progenitores de la población de galaxias elípicas masivas del universo local.
In this talk, I will show the recent results obtained in deep ALMA observations of the explosive outflow located in the heart of the Orion Nebula, the Orion Kleinmann-Low Nebula (Orion KL). These observations revealed over a hundred arcsecond wide and tens of arcseconds long high-velocity 12CO (J=2−1) streamers that approximately point to a central region where a young stellar massive system disintegrated very recently. The kinematics and morphology of the molecular streamers confirmed the explosive nature of the outflow in Orion KL. The energetics of the explosive outflow require the formation of a binary with an AU-scale or smaller semi-major axis. This event may have led to stellar merger which powered the explosion in the gas. Finally, I will show the latest efforts to reveal more cases where possible mergers events could led explosive outflows like the one in Orion KL.
I present an observational study of a sample of radio AGN sources. I study their radio polarization properties in a wide frequency range by observing with the 100-m Effelsberg telescope and the Very Large Array (VLA) interferometer. The aim was 1) to define a sample of candidates to contain an extreme environment around the SMBH and, 2) to study their environment by modeling of the polarization properties within a wide frequency range. I select sources with no detectable flux polarization at 1.4GHz in the NVSS survey, characteristic of strong depolarization due to a high value of Rotation Measure (RM) and thus, of an extreme medium in these sources. I performed single dish observations at 10.45 GHz using the 100-m Effelsberg telescope. At this high frequency, I detected polarized flux density on 30 sources, which became our high-RM candidates. Single dish follow-up in the 2 to 15 GHz frequency range, were performed to characterize their radio spectra and to determine their RMs. The polarization angle behavior deviates significantly from the lambda^2 law, suggesting that several Faraday screens are present in the intervening medium. I studied the most interesting high-RM cases through wide-band high sensitive observations at C and X bands using the JVLA. I modeled the polarization properties constructing a set of models which are combinations of simple internal and the external Faraday screens. This new approach of polarization study allows to spectrally resolve multiple polarized components of unresolved AGN with the result to trace some clumpy and dense region surrounding them. This new spectropolarimetry approach can be adopted as a new way to trace clumpy and dense regions surrounding the AGN. Moreover, I will present a new project I am involved in which this new spectropolarimetry study is applied to a very specific class of objects: the Compact Symmetric Objects (CSOs), the nature of which is still matter of debate. Indeed, whether they are young radio sources (youth scenario) or compact radio sources embedded in a very dense medium (the frustrated scenario), is not clear yet. The Stokes Q and U modeling will help to understand which of the two scenario is the most probable. I will explain the “engulfed cloud model”, proposed by Begelman 1999 which is in favor of the youth scenario and that it could be tested with this new spectropolarimetry approach.

Diciembre

8

Alfonso Trejo, Academia Sinica
Próximo Coloquio

Las estrellas AGB contribuyen de manera importante a la tasa total de masa de polvo que es inyectada al MIE de las galaxias. Estimaciones de esta inyeccion han sido hechas para el caso de las Nubes de Magallanes, usando observaciones del telescopio Spitzer. Sin embargo, la ultima estimacion de la tasa de inyeccion de polvo en la Via Lactea fue hecho a finales de los ochenta, para una muestra que no cubre todo el cielo. En este trabajo revisamos la tasa total de perdida de polvo de estrellas AGB en la vecindad solar. Es especialmente dificil obtener distancias a estrellas AGB 'polvosas', ya que no se encuentran en los catalogos de Hipparcos, debido a la alta exticion en su medio circunestelar. Usando los catalogos de WISE, 2MASS y otros, construimos distribuciones de energia a varias longitudes de onda para todas las estrellas AGB localizadas a una distancia maxima de 1 kpc. Para el calculo de la tasa de perdida de masa, usamos la malla de modelos GRAMS. En esta platica mostramos resultados de el numero total de estrellas AGB en la vecindad solar y su tasa total de perdida de masa. Tambien mostramos una comparacion entre las distancias de brillo que obtenemos y las reportadas en la literatura usando varias tecnicas observacionales.
9
Especial

Emilio Tejeda, IA-UNAM
Coloquio Especial

Se piensa que prácticamente todas las galaxias alojan un agujero negro supermasivo en sus centros. No obstante, la evidencia directa que tenemos sobre su existencia es escasa puesto que la mayor parte de estos objetos se encuentran en una fase inactiva. Una oportunidad única para estudiar a esta población de agujeros 'durmientes' se presenta ocasionalmente cuando una estrella se acerca lo suficiente al agujero negro central y es desgarrada por las fuerzas de marea de éste. En esta plática presentaré características tanto teóricas como observacionales de este tipo de fenómenos. Así mismo discutiré algunos de los retos que se presentan al estudiar estos encuentros numéricamente y presentaré ejemplos de simulaciones recientes que modelan un evento de este tipo de principio a fin. 

Enero

15

Vicente Rodríguez, Harvard-Smithsonian Center for Astrophysics (CfA)

En el modelo cosmológico actual (Lambda-CDM) la estructura crece jerárquicamente, por lo cual las fusiones entre galaxias son un ingrediente esencial de cualquier modelo de formación de galaxias. Una determinación precisa de la tasa de fusión entre galaxias es necesaria para explicar la distribución morfológica de las mismas, así como la frecuencia de objetos muy luminosos en el Universo temprano, como galaxias con brotes de formación estelar y núcleos activos de galaxias. Aunque la tasa de fusión entre halos de materia oscura ya está determinada con bastante precisión, gracias a avances en simulaciones de N cuerpos durante la primera década del milenio actual, hace falta una medición igualmente precisa de la tasa de fusión entre galaxias, ya que distintas predicciones teóricas presentan diferencias de alrededor de un orden de magnitud entre ellas.

En este estudio hemos usado simulaciones del proyecto Illustris, un conjunto de simulaciones hidrodinámicas de gran escala realizadas con el código de malla móvil AREPO, para construir árboles de fusiones de galaxias y con ellos calcular la tasa de fusión entre galaxias como función de la masa estelar del descendiente, el cociente entre las masas de los progenitores, y el corrimiento al rojo. Encontramos que la tasa de fusión entre galaxias tiene una forma matemática relativamente sencilla y que su evolución con respecto al corrimiento al rojo es consistente con observaciones de pares de galaxias medianas (M* > 10^10 Msun). La variación de la tasa de fusión con respecto a la masa estelar de la galaxia descendiente es consistente con observaciones recientes del estudio GAMA (GAlaxy and Mass Assembly). Finalmente, proporcionamos una función analítica para la tasa de fusión que es precisa sobre un rango amplio de masas estelares, cocientes de masa y corrimientos al rojo.

30
Viernes

Carlos Román, IA-UNAM Ensenada
Coloquio Especial

La UNAM entró en 2012 a la cuarta fase del catastro Sloan Digital Sky Survey (SDSSIV), como miembro del consorcio con todos los privilegios. Siendo uno de los proyectos más productivos en la astronomía en las últimas décadas, nuestra participación representa una gran oportunidad. En esta charla hablaré de uno de los cuatro proyectos principales del SDSSIV, llamado Apache Point Galactic Evolution Experiment (APOGEE-2) cuya segunda fase recién comenzó. APOGEE-2 es un catastro espectroscópico en alta resolución, en el cercano infrarrojo, de todas las componentes galácticas, basado principalmente en estrellas gigantes (cerca de 0.25 millones de fuentes), pero que se extiende incluso a estrellas tardías (enanas tipo K y M) y a estrellas muy jóvenes en regiones de formación estelar. Hablaremos de las generalidades del consorcio SDSS, de las metas y sub-proyectos de APOGEE-2, y de cómo podemos (y debemos) participar en él.

Febrero

I am presenting the results from the "Herschel Exploitation of the Local Galaxy Andromeda" (HELGA), a survey who observed our neighbour galaxy M31 in five IR bands. Taking advantage of Herschel sensitivity and spatial resolution, we address various issues related to the dust distribution and properties in Andromeda, and its relation to the spatial distribution and characteristics of the gas and stellar components. Dust in M31 extends well beyond its optical radius, and is gathered in well-defined recurrent patterns. Contrary to what is found in other galaxies, dust reaches the highest temperatures in the bulge, heated by the old stellar populations, and its (chemical) properties change radially. Using a panchromatic dataset we adopt physically consisted panchromatic model to fit the broad-band SED of each pixel in our data, to address the origin of dust scaling relations, at the spatial level of giant molecular clouds.

12

Wolfgang Steffen, IA-UNAM, Ensenada

Mostramos algunos resultados representativos de aplicaciones recientes del software Shape. En los últimos años este programa se ha convertido en un laboratorio astrofísico virtual interactivo con un espectro de aplicaciones muy amplio. Su aplicación principal es el modelado tridimensional para analizar e interpretar observaciones de objetos particulares en base al modelado manual en un espacio 3D virtual. Además, el programa incluye un módulo de hidrodinámica básica, transporte radiativo y básicas funciones de fotoionización, entre otros.

La interactividad permite su aplicación cómo herramienta demostrativa visual en clases de astrofísica ilustrándose de manera directa una amplia gama de fenómenos astronómicos teóricos y observacionales. Una característica clave de Shape es que el usuario no necesita interactuar con el código del programa. Todas las funciones de realizan mediante la interfaz gráfica.

Mediante el uso de simulaciones numéricas de grumos densos y masivos con fluctuaciones iniciales de velocidad y/o densidad, mostramos que la función de masa de las partículas sumideros sigue una ley de potencias con pendiente $dN/d\log M \propto M^{\Gamma}$, $\Gamma = -1 \pm 0.1$, independientemente del número de Mach inicial. Esta dependencia concuerda con el límite asintótico encontrado por Zinnecker suponiendo acreción de Bondi-Hoyle-Littleton (BHL). Aunque la acreción BHL no es aplicable estrictamente debido a la complejidad y variabilidad del ambiente que rodea a cada partícula sumidero, argumentamos que las FMI son el resultado de una dependencia de la tasa de acreción con $M^2$, al menos por grupos de estrellas. Aunque hemos simplificado la ecuación de estado, y evitado procesos adicionales como transferencia radiativa y calentamiento estelar, nuestras simulaciones enfatizan la importancia del enfocado gravitacional para la formación estelar masiva.

24
Martes

Pablo Velázquez, Instituto de Ciencias Nucleares (ICN-UNAM)
Coloquio Especial

Modelamos el remanente de la SN 1006 mediante simulaciones magnetohidrodinámicas en 3D. A partir de los resultados numéricos, hicimos un estudio de la emisión polarizada en radiocontinuo, obteniendo mapas sintéticos de la emisión polarizada, el parámetro de Stokes Q y del ángulo de posición del campo magnético, los cuales se comparan con las observaciones. En el cálculo de la emisión en sincrotrón, consideramos los dos posibles mecanismos de aceleración de las partículas relativistas: el cuasiparalelo y el cuasiperpendicular. La comparación de nuestro mapa sintético del parámetro Q con el observado, muestra que el mecanismo de aceleración responsable de la emisión en radio de este remanente es el cuasiparalelo, removiendo la ambigüedad que había en estudios previos.

Marzo

Traditionally its been considered that turbulence in molecular clouds provides support against self-gravity. In order to do so, turbulence should be random, microscopic and isotropic. However, it is highly uncertain which sources of energy may provide such kind of turbulence, since it is highly dissipative, and most of the energy is involved at the largest scales, which furthermore, imply that it cannot be isotropic. In the present contribution we will discuss a set of observational and theoretical results, namely, the column density PDF, scaling relations, fragmentation of clouds into clumps and clumps into cores, formation and evolution of clouds and cores, Virial type relations, etc., which strongly suggest that nonthermal motions within molecular clouds, rather than kinetic energy providing support against collapse, might be very well the result of hierarchical and chaotic collapse

12

Gustavo Romero, Universidad de La Plata

Some young open clusters and giant molecular clouds have been detected as gamma-ray sources in recent years. The level of gamma radiation suggests the existence of local injectors of cosmic rays in these objects. I will discuss the contribution of massive runaway stars and other supersonic objects to the cosmic ray population in young clusters and the origin of the observed gamma-ray emission.

Empleando una muestra limitada por volumen de mas de 30,000 galaxias proveniente del SDSS DR7, hemos investigado el medio ambiente de galaxias barradas, empleando un variado conjunto de estadísticas. Al dividir nuestras galaxias de acuerdo a su tipo morfológico, encontramos que las galaxias barradas de tipo temprano muestran una tendencia débil pero significatíva a sobreagruparse en escalas entre 100 kpc a 1 Mpc cuando comparamos su distribución con galaxias de tipo temprano no barradas, lo cual indica que la presencia de barras en galaxias de tipo temprano depende de sus posiciones dentro de los halos de materia obscura que las contienen. Para galaxias barradas tardías, encontramos que presentan menos vecinas cercanas en escalas menores a 500 kpc que sus similares no barradas, lo que sugiere que fuerzas de marea de compañeras cercanas suprimen la formación/evolución de las barras. Para galaxias centrales de tipo tardío encontramos que la fracción de galaxias con barras fuertes depende fuertemente tanto del espín galáctico como del cociente masa estelar/masa del halo, de forma que las galaxias con valores entre bajos a intermedios de espín y con discos estelares relatívamente masivos en relación a sus halos de materia obscura, presentan fracciones de galaxias barradas mas altas que aquellas con altos valores de espín y bajos valores del cociente masa estelar a masa del halo obscuro. Finalmente, no encontramos ninguna relación obvia entre la presencia de barras estelares en galaxias con la estructura a gran escala del Universo.

26

Peter Otto Hess, Instituto de Ciencias Nucleares (UNAM)

Se presenta una extensión de la Relatividad General en la cual se propone que la masa no solo curva el espacio sino también cambia la estructura del vacío. Esto resulta en la presencia de una energía oscura cuya densidad aumenta hacia menores distancias radiales. El efecto tiene su justificación en la Mecánica Cuántica semi-clásica, pero también resulta de una teoría propuesta por nosotros, llamada Relatividad General seudo-compleja. La presencia de la energía oscura tiene una influencia importante sobre la apariencia del disco de acreción para un observador muy lejos. Presento una breve introducción a la teoría de Relatividad General seudo-compleja y posteriormente una descripción para el disco de acreción de Page y Thorne. Una de las predicciones importantes es la apariencia de un anillo oscuro en el disco de acreción.

Abril

9

Jesús Toalá Sanz, Instituto de Astrofísica de Andalucía (IAA-CSIC)

En esta charla presentamos nuestros resultados numéricos más recientes sobre la emisión de rayos X de Nebulosas Planetarias. Para esto, desarrollamos simulaciones radiativo-hidrodinámicas en 2D de alta resolución para estudiar la formación y evolución de burbujas calientes en estos objetos. Tomamos en cuenta la evolución detallada de la estrella central y sus parámetros estelares desde los últimos pulsos térmicos durante la etapa de la rama asintótica de las gigantes (AGB) hasta la etapa post-AGB para diferentes masas iniciales. Utilizamos el código CHIANTI para calcular los parámetros observables en rayos X (espectros sintéticos, luminosidades, temperaturas, etc) para comparar directamente con observaciones. En particular, hacemos una comparación directa con los resultados observaciones del proyecto CHANPLANS (The Chandra Planetary Nebula Survey).

We model the vertical structure of magnetized accretion disks subject to viscous and resistive heating, irradiation by the central star and magnetic pressure. We apply our formalism to the radial structure of magnetized accretion disks threaded by a poloidal magnetic field developed by Shu and coworkers. We consider disks around low mass protostars, FU Ori and T Tauri stars. We tested our formalism using different mass-to-Magnetic flux ratios and I will show how this essential parameter can strongly modify the disks structure.

23

We present the results of our mutlifrequency observations with the GMRT and the VLA of five large radio galaxies. These observations were made with the objectives of estimating their spectral ages and examining any evidences of diffuse extended emission at low radio frequencies due to an earlier cycle of

activity. While no evidence of extended emission due to an earlier cycle of activity has been found, the spectral ages have been estimated to be > 15 Myr for the oldest relativistic plasma seen in the regions close to the cores in these large sources. The spectra in the vicinity of the hotspots are somewhat steeper than theoretical expectations.

Mayo

4
Lunes

Luis A. Aguilar, IA Ensenada - UNAM
Coloquio Especial

Our view of the structure and dynamics of our Galaxy has progressed, pushed by the acquisition of ever larger datasets that encompass wider perspectives. At the dawn of the Gaia era, we are about to enter a phase of unprecedented detail in our view of our Galaxy. This opens up the possibility of using new analysis tools, or the use of traditional tools at newer scales. However, to extract the most of the Gaia database, it is necessary to immerse our theoretical models within Gaia mock catalogues to derive proper inferences about the structure of our Galaxy. In this talk we will review several tools developed by our group to construct and analyze realistic Gaia mock catalogues and some of the lessons we have learnt from them. In particular, we will present applications to the problems of characterizing the central bar of our Galaxy, the warp in the Galactic disk and identifying substructure in the stellar halo.

7

Mauricio Tapia, IA Ensenada - UNAM

Se presentarán observaciones en el infrarrojo, desde 1 hasta 500 micras, describiendo las características de varias regiones de reciente, y no tan reciente, formación estelar. En muchas de ellas se encuentra un patrón recurrente en su historial: Aparecen estadíos bien definidos de "brotes" de nacimiento estelar dentro de un mismo ambiente, que en ocasiones es complejo y en otras es más simple. Normalmente, la primera generación contiene estrellas muy masivas que perturban el ambiente, dando como resultado una segunda generación con un cúmulo embebido de mediana masa, al tiempo que aparecen núcleos densos formando activamente estrellas en la actualidad.

26
Martes

Jan Forbrich, Universidad de Viena
Coloquio Especial

The Orion Nebula Cluster (ONC) is hosting a zoo of radio sources that has been known for decades. Additionally, the X-ray properties of its substantial YSO population have been studied in detail in the Chandra Orion Ultradeep Survey. With the advent of the newly expanded NRAO Very Large Array, we have returned to the ONC with deep simultaneous radio and X-ray observations using the VLA and Chandra. With this massive dataset, we have begun to obtain a deep census of radio sources in this region, including information on polarization and spectral indices, to systematically study YSO radio variability on time scales shorter than an hour, and to put this into the context of X-ray light curves and other source properties. Additionally, we have assembled a wealth of infrared data to assist the interpretation, including a new deep near-infrared survey (VISION) and Spitzer mid-infrared variability data obtained as part of the YSOVAR program. After presenting first results of the radio-X-ray program, I will finally discuss the prospects for radio-X-ray-IR variability studies of YSOs.

Se presenta un trabajo que analiza el Anuario del Observatorio Astronómico Nacional de Chapultepec -primera época- en el que se manifiesta como un punto de intersección de objetivos políticos, científicos, sociales y educativos, en términos de intercambio de difusión y divulgación del conocimiento; el Anuario, también se presenta como un medio a través del cual se integraron las redes científicas locales, nacionales e internacionales con las cuales se intercambio conocimiento.

La revista, revela el papel de la cultura impresa con una imagen nítida de las practicas científicas que se desarrollaron en esa época y en las que predominan las desarrolladas por los astrónomos mas destacados del último tramo del siglo XIX (1880-1900).

El texto que se abordó desde una perspectiva socio-histórica, da cuenta de la vida social y cultural que posibilitó los avances en el campo de la astronomía, así como el papel que jugó México dentro de las comunidades científicas de la época.

Finalmente se abordará el tema de la circulación del conocimiento, en donde el Anuario también muestra su función pedagógica, dirigido a un público en general, así como a la comunidad científica que respondió a la política educativa del régimen.

Junio

The key project “Chemical HErschel Surveys of Star form- ing regions” (CHESS), takes full advantage of the new opportunity offered by Herschel/HIFI and explores in a systematic way the frequency range between 480 and 1902 GHz in several star-forming regions. The goal of the project is to provide the first ever spectral census of this frequency range in a selected sample of sources covering the principal parameters and aspects of the star-formation process: mass of the forming star, its evolutionary status, and the interaction with the surroundings. In this talk I will focus on the results of the interstellar shock L1157-B1, in particular the studies of molecular species such as CO, H2O, CS, N2H+, among others.

11
Jueves

Antonio Hernández Gómez, Karina Maucó Coronado, Raul Naranjo Romero, Carlos Tapia Schiavon, Jorge Alejandro Tarango Yong,
Coloquio Especial

La emisión de polvo en discos protoplanetarios ocurre a distintas escalas espaciales. La región interna del disco emite preferentemente en el IR y en particular la emisión en el cercano infrarrojo proviene de la pared de sublimación, la cuál corresponde a la zona más interna dentro del disco donde el polvo aún no se ha evaporado. La emisión en el mm proviene principalmente de las regiones externas y frías del disco.

Para el primer caso presentaré un estudio de variabilidad en el cercano IR asociado a cambios en la estructura de la pared de sublimación, enfocado a 3 fuentes (LRLL 32,40 y 63) de la región jóven de formación estelar IC 348.

Para esta misma región presentaré un proyecto que se está realizando con gente de la Universidad de Massachussetts con datos del Gran Telescopio Milimétrico que arrojará información estadística de la masa de los discos.

Julio

Las estrellas masivas sufren intensos episodios de pérdida de masa a lo largo de su evolución enriqueciendo fuertemente el medio circundante. Debido a la interacción de los vientos se forman nebulosas ionizadas que condicionan cómo los nuevos metales sintetizados se dispersan y mezclan en el gas original en que se formó la estrella.

En la primera parte de la charla mostraré el estudio realizado con espectroscopía de campo integral en dos nebulosas alrededor de estrellas masivas (NGC6888 y M1-67) con el objetivo de obtener información relevante tanto de los procesos estelares internos como de la interacción de los vientos en las diferentes etapas evolutivas.

En segundo lugar describiré el trabajo realizado sobre una muestra de regiones HII del anticentro Galáctico que nos ha permitido obtener gradientes de abundancias químicas para analizar la evolución y el enriquecimiento químico de la Vía Láctea.

Agosto

6

Enrique López-Rodríguez, Universidad de Texas San Antonio

The new generation of sub-arcsecond resolution infrared (IR) polarimetric instruments, CanariCam on the 10.4-m Gran Telescopio CANARIAS (GTC) and MMT-Pol on the 6.5-m MMT, have opened a new window to reveal the cores of active galactic nuclei (AGN). Using both instruments, we have been able to 1) discover a highly polarized synchrotron core in Cygnus A, 2) study the torus of NGC 1068 as a hydromagnetical outflow wind, and 3) investigate the interaction of the jet with the ionization cones in NGC 1068. This talk will introduce the polarimetric modes of CanariCam and MMT-Pol, what can be learnt from polarimetric techniques observations, and the latest results on the study of AGN using IR polarimetric techniques.
20

Alvaro Sanchez-Monge, Universidad de Colonia

Establishing an evolutionary sequence for high-mass young stellar objects is one of the hot topics of current star formation. Differently to the low-mass star formation case, high-mass stars reach the zero-age main sequence while they still undergo heavy accretion, and their powerful radiation pressure should halt the infall of material, thus inhibiting growth of the stellar mass beyond 8 Msun. Recent theories, however, propose that high accretion rates and/or accretion through massive disks could overcome this problem, and explain the formation of stars with masses up to 140 Msun. In this talk I will characterize, from an observational point of view, an evolutionary scheme for the massive star formation process: which starts with dense cores with almost no (star-formation) activity, and ends with the development of HII regions that disrupt their natal cloud. I will present recent results on the physical properties of dense cores, molecular outflows, circumstellar disks, and HII regions obtained with a number of different instruments including the Atacama Large Millimeter Array.

27

Jill Naiman, (ITC) Harvard-Smithsonian Center for Astrophysics

The effective supply and retention of gas in shallow gravitational potentials is a problem with implications in a diverse set of astrophysical systems. In particular, the magnitude of gas flows into mature dwarf galaxies can have large impacts on the star formation histories in these systems. In this talk, computational techniques will be used to show how such such weakly bound gravitational structures might be able to accumulate gas effectively. The implications for star formation in dwarf galaxies after their incorporation into a larger host halo will be presented.

Septiembre

3

Gabriela Montes, Universidad de California Santa Cruz (UCSC)

The particular astrophysical site where r-process nuclei are synthesized remains open to more than one interpretation, being both type II supernovae and neutron-star binary mergers two likely astrophysical sites. These two mechanisms synthesized different quantities of r-process material and these differences should give rise to clear signatures in the enrichment pattern of r-process elements in galaxies and may ultimately help to constrain the dominant production mechanism. In this talk, a comparison between the propagation of the material ejected from both events will be presented. The enrichment of r-process material from these two mechanisms is analyzed in order to investigate the distribution of these nuclei along the galaxy.
Los Núcleos Activos de Galaxias (AGN por sus siglas en inglés), localizados en el núcleo de alrededor de 30-40% de las galaxias observadas, generan una cantidad extremadamente grande de energía (del orden de 10^3-4 veces la energía integrada que producen las otras componentes de la galaxia). Los AGN son objetos compactos condensados en pequeñas distancias (~ 10^16-18 cm), sus masas se encuentran en el intervalo de 10^6-10^10 masas solares. En teoría, los AGN son agujeros negros súper masivos que acretan su material mas cercano. En varias galaxias con AGN se ha detectado interacción directa de materia y energía entre el núcleo y el resto de la galaxia, tal interacción podría cambiar la tasa de formación estelar de la galaxia y producir retroalimentación, debido a la mezcla de material que evolucionó en el AGN y el material de la galaxia. Ambos materiales evolucionaron en dos medios drásticamente distintos: mientras que el material del AGN evolucionó en procesos energéticos duros, el material de la galaxia evolucionó principalmente en procesos de formación estelar. En el coloquio se presentará un estudio de 5 AGN seleccionadas de una muestra de 28 galaxias con AGN tipo 1, sus espectros de rayos X muestran absorción ionizada producida por material eyectado del núcleo. El objetivo es revisar que tan plausible es el escenario donde el material ionizado del AGN alcanza el resto de la galaxia y con ello, cambie la historia de evolución de la galaxia anfitriona.
Usando simulaciones MHD y de dinámica estelar, estudiamos la respuesta del disco gaseoso a dos modelos de potenciales espirales bisimétricos: una perturbación cosenoidal y el modelo PERLAS. La principal diferencia está en el número de brazos generados en el gas; mientras que el modelo cosenoidal siempre genera dos brazos gaseosos, PERLAS genera cuatro. Aunque la duplicación de brazos ha sido explicada como resultado de resonancias ultra-armónicas, estudios de órbitas periódicas nos llevan a una explicación alternativa: la formación de ramas en los brazos espirales puede ser una señal de que los brazos son transitorios.

Octubre

1

Luis Felipe Rodríguez, IRAf - UNAM

The recent decades have witnessed major advances in our understanding of the formation of solar-mass stars. However, the formation mechanisms of stars at the extremes of the mass range, that is, on one hand very massive stars and on the other brown dwarfs, remain poorly understood. I will summarize the main observational results presented in a meeting on massive star formation that took place in Puerto Varas, Chile and discuss some new observational perspectives for the future.
27
Martes

Andrés Felipe Pérez-Sánchez , IRyA - UNAM
Coloquio Especial

The evolution of the circumstellar envelopes of AGB and post-AGB is yet poorly understood. In particular, the mechanism(s) responsible for shaping the axisymmetric circumstellar envelopes observed towards bipolar Planetary Nebula sources remain unknown. The study of the collimated, high-velocity outflows observed towards post-AGB sources known as Water Fountain nebulae, could provide important clues about the nature of the engine shaping their circumstellar envelopes. In this colloquium I will present new results from ATCA and JVLA observations towards two representative members of the still small group of (16 confirmed up to date) Water Fountain sources.
29

Gerardo Andrés Pech Castillo, IRyA - UNAM

Noviembre

During the last decades protostellar jets have been intensively studied at radio wavelengths. It is now well established that young stellar objects (YSOs) in their earliest stages emit radio emission at cm wavelengths which is associated with free-free emission from the base protostellar jets. Since these objects are deeply embedded in large amounts of dust and gas surrounding the protostar, radio observations have revealed as the best way to study the phenomena that takes place very near the protostar. We have now been able to study the environment of these protostars up to physical scales of only a few AU. However, as we have performed higher sensitive and higher angular resolution observations, we have also been able to discover new phenomena which, not only, have important implications for the star formation theory, but also add new interesting questions. Here, I will talk about two important results we have obtained in two star-forming regions. The first one, the discovery of synchrotron emission from a protostellar jet, imply that protostellar jets are able to accelerate particles up to relativistic velocities, even when these objects are considered the least powerful between astrophysical jets (AGN jets, micro quasars, etc..). Moreover, the detection of linearly polarized emission allows to study the magnetic field, one of the most important ingredients in the jet formation and collimation, but yet, one of the most unknown parameters in star formation. The second results is the observation, in real time, of the collimation of a protostellar wind, posing interesting questions on how jets are collimated in these systems.
12

Héctor Otí Floranes, IRyA - UNAM

The understanding of the Lyman alpha emission (Hydrogen n:2->1) in starburst galaxies needs multi-wavelength analysis of nearby sources with high-spatial resolution. The international project Lyman Alpha Reference Sample (LARS) was defined to carry out such task. In this talk I will describe the intriguing nature of Lyman alpha emission, and the observational limitations we face. The core of the talk will be the review of the most important results obtained by LARS so far, which have led to confirm that Lyman alpha escape is a multiparametric problem.
19

Gabor Orosz, Kagoshima University

This colloquium will focus on water fountains, huge stars with collimated and high-velocity outflows, moments before their deaths as white dwarfs enveloped in beautiful planetary nebulae. I am going to present recent astrometric results from the fastest and farthest water fountain, and through that we will discuss 1, how VLBI astrometry using maser emission helps us to study water fountains 2, the morphology of water fountain outflows 3, the variability of water maser emission and 4, how all of these tell us something about the evolutionary link between AGBs and PNe.
26

José Miguel Rodríguez Espinosa, IAC - España

I will start with a brief description of the GTC, the 10.4m telescope that Mexico has access to it. The I will discuss the projects that we are undertaking using GTC data. In particular, the search for high-z Lyman α sources in the SHARDS survey. Finally I will talk about another project which aim is the study of Lymanα sources at the epoch in which re-ionization was being completed. I will show the discovery of an overdensity of sources, that will eventually become a cluster similar to or larger that the Coma cluster.

Diciembre

8
Martes

Shane O'Sullivan, IA - UNAM Cd. Universitaria
Coloquio Especial

Substantial progress in our understanding of AGN jets has been made in recent times, particularly in relation to the conditions required for efficient jet formation, as well as our knowledge of the three-dimensional magnetic field structure of the jet. I will review our current understanding of AGN jets before presenting new radio polarization and Faraday rotation observations of radio-loud AGN from parsec to kiloparsec scales. I will show the importance of full-Stokes, broadband radio observations in providing important constraints on fundamental jet parameters such as the jet magnetic field strength, it's 3D structure, and the amount of magnetic flux at the jet launching site
I will show scaling relationships between fundamental properties of galaxies such as the mass, metallicity, SFR, SSFR, and HI mass. I will introduce the GAMA survey, the Z-SSFR relation, and will talk about a model based on this relationship. Finally, using data from the SDSS, GAMA and ALFALFA surveys, we estimate oxygen yields based on the HI and metallicity measurements of a sample of ~4500 galaxies and analyze the impact of inflows and outflows in galaxies.

Enero

9

Emilio Romano-Díaz, Argelander-Institut für Astronomie (AIfA, Alemania)

La emisión extendida de radiocontinuo en regiones de formación estelar masiva esta usualmente dominada por la emisión libre-libre de la region HII asociada. Sin embargo, cuando se observa con un interferometro de alta resolución angular, la emisión extendida se cancela y una diversidad de objetos compactos son detectados y estudiados. Estos objetos compactos incluyen a las regiones HII hipercompactas (emisión libre-libre), a las estrellas de baja masa con actividad magnetosférica (emisión girosincrotrón) y a las interfases de colisión viento-viento en sistemas binarios masivos (emisión sincrotrón). Discutimos como se pueden estudiar y caracterizar estas regiones y que información obtenemos de ellas. En particular, hay dos nuevos tipos de objetos compactos de radio cuya naturaleza no esta clara aún y que podrían revelar nuevos fenómenos.
Most stars -- and hence most solar systems -- form within groups and clusters. The first objective of this talk is to explore how these star forming environments affect solar systems forming within them. The discussion starts with the dynamical evolution of young clusters with N = 100 - 3000 members. We use N-body simulations to study how evolution depends on system size and initial conditions. Multiple realizations of equivalent cases are used to build up a robust statistical description of these systems, e.g., distributions of closest approaches and radial locations. These results provide a framework from which to assess the effects of clusters on solar system formation. Distributions of radial positions are used in conjunction with UV luminosity distributions to estimate the radiation exposure of circumstellar disks. Photoevaporation models determine the efficacy of radiation in removing disk gas and compromising planet formation. The distributions of closest approaches are used in conjunction with scattering cross sections to determine probabilities for solar system disruption. The result of this work is a quantitative determination of the effects of clusters on forming solar systems. The second objective of this talk is to use these results to place constraints on the possible birth environments for our own solar system.

Febrero

Es ampliamente aceptado que la función de distribución de las masas de los cúmulos estelares jóvenes es universal, y puede ser interpretada como una función de distribución de densidad de probabilidad con un límite de masa superior constante. Como resultado de esta visión, las masas de los objetos máas masivos estarían determinadas por el tamaño de la muestra. Por el contrario, mostramos con un alto grado de confianza que las masas de los cúmulos jóvenes (< 10 Maños) más masivos en la galaxia floculenta M 33 decrecen al aumentar el radio galactocéntrico, en contradicción con un límite superior constante de la función de masa. Además, al comparar las distribuciones radiales de densidades superficiales de gas, por un lado, y de los cúmulos más masivos, por el otro, encontramos que están correlacionadas. Por lo tanto, podemos descartar la formación estelar estocástica en M 33. El cambio en la masa máxima de los cúmulos estelares ahí debe tener causas físicas, i.e., los cúmulos muy masivos parecen requerir condiciones físicas especiales, como densidades superficiales altas de gas, para poder formarse.
La gran mayoría de fuentes extragalácticas detectadas por el satélite de rayos gamma Fermi son AGNs con jets relativistas prominentes. Estudios multi-frequencia sugieren que la producción de rayos-gamma ocurre en las partes más internas de los jets relativistas (i.e. radio core). Estas regiones no aparecen resueltas en mapas de alta resolución angular (e.g. VLBI a 7mm), lo cual complica la interpretación y modelado de los mecanismos de emisión de rayos-gamma. Sin embargo, esto está por cambiar gracias al Event Horizon Telescope (EHT) que es una red de VLBI que actualmente opera a 1mm. En esta charla se discutirán las preguntas que permanecen abiertas con respecto a la producción de altas energias en AGNs y se mostrarán ejemplos específicos en donde observaciones de super alta resolución angular con el EHT podrían restringir la región en el jet donde la radiación gamma es generada. Además, reportaremos el primer experimento de VLBI con el GTM realizado durante el verano del 2013.

Marzo

6

Tatiana Niembro Hernández, Instituto de Geofísica, UNAM

Las eyecciones de masa coronal (CMEs) son erupciones esporádicas de la atmósfera solar debidas a cambios en el campo magnético. El estudio de las CMEs y su interacción con otras estructuras de gran escala, es de suma importancia para entender la dinámica del plasma en el medio interplanetario y para predecir el clima espacial. En esta plática, presentaré un modelo analítico para describir la evolución de dos CMEs consecutivas que colisionan en el medio interplanetario. En este modelo, suponemos que las CMEs son perturbaciones que viajan en un medio homogéneo supersónico y superalfvénico, de tal forma que, las variaciones de la temperatura y del campo magnético son despreciables. Estas perturbaciones forman superficies de trabajo cuya evolución depende de sus parámetros iniciales como la velocidad, la densidad y su duración. Si la segunda CME viaja más rápido que la primera, las superficies de trabajo se alcanzan formando una región de presión constante cuya evolución dependerá de las condiciones iniciales de ambas superficies de trabajo. Describiré las ecuaciones y la aplicación del modelo a un evento de interacción observado el 23 de mayo del 2010. El modelo predice el arribo a 1 UA de la estructura compleja formada durante la colisión, con un error menor a una hora y 50 km/s para el tiempo y velocidad respectivamente. También presentaré algunos avances de los resultados obtenidos con una simulación numérica del mismo evento.
13

Juan José Downes, Instituto de Astronomía Ensenada

27

Edgar Castillo Dominguez, INAOE

Abril

8
Martes

Sergei Kalenskii, Astro Space Center de Moscú

10

Santiago Torres, Instituto de Astronomía CU

24

Carl Melis, Center for Astrophysics and Space Sciences (UC San Diego)

The Pleiades is the best studied open cluster in the sky. It is one of the primary open clusters used to define the "Zero Age Main Sequence", and hence it serves as a cornerstone for programs which use main-sequence fitting to derive distances. This role is called into question by the "Pleiades distance controversy" - the distance to the Pleiades from Hipparcos of about 120 pc is significantly different from the distance of 133 pc derived from other techniques. Although this amounts to a 10% difference in the distance, the resultant discrepancies as propagated into the Pleiades HR-diagram, and the necessary revisions of physical models to obtain agreement with the Hipparcos result, are quite significant. To resolve this issue we are carrying out a VLBI program to derive a new, independent trigonometric parallax distance to the Pleiades. We have now obtained the most accurate and precise cluster distance to date which is incompatible with the cluster distance suggested by Hipparcos.
28
Martes

Omaira González Martín, Instituto de Astrofísica de Canarias (IAC)

Es ampliamente aceptado que todas las familias de núcleos activos de galaxias (AGN) comparten un mismo mecanismo físico. Esto es conocido como el modelo unificado de AGNs. El componente esencial de este modelo es una estructura de polvo (simplificada como un toro) que oscurece las partes internas del AGN, impidiendo en algunas ocasiones la visión directa del mismo. Este toro es el responsable de la dicotomía entre AGNs Tipo-1 y Tipo-2. Sin embargo, este modelo unificado es incapaz de explicar todas las clases de AGN. En particular, las clasificaciones obtenidas en el óptico y en rayos X no siempre son consistentes. El objetivo de nuestro estudio es analizar la correspondencia entre las clasificaciones ópticas y los espectros de rayos X para una muestra de AGNs cercanos. Por primera vez hemos hecho este análisis sin modelar los espectros en rayos X. Esto tiene la enorme ventaja de no asumir ningún modelo físico que pueda sesgar nuestros resultados. Para ello hemos usado una red neuronal. Los resultados son: ¿Es posible que todas las galaxias contengan un núcleo activo? Más del 80% de los espectros con líneas de emisión tienen una componente de AGN, a pesar de que muchos de ellos están clasificados como no activos en el óptico. Esto significa que la fracción de AGNs en el Universo local puede ser mucho mayor de lo que se pensaba hasta ahora. ¿Se distinguen en rayos X las clases encontradas en el óptico? La mayoría de las clasificaciones ópticas muestran espectros en rayos X claramente diferenciados en promedio. Esto puede ser muy útil para surveys en rayos X (por ejemplo eRosita), donde la información óptica no está disponible puesto que nuestra red neuronal puede dar la clasificación óptica basada en la información en rayos X. ¿Es el oscurecimiento un ingrediente importante para distinguir las clases ópticas? De manera natural la red neuronal encuentra un continuo de clasificaciones entre los objetos Tipo-1 y los objetos Tipo-2 que está relacionado con el oscurecimiento de la fuente. Por tanto, el oscurecimiento aparece como uno de los ingredientes principales para agrupar las clases ópticas, tal y como predice el modelo unificado de AGNs.

Mayo

En esta plática presentaré los resultados de un rastreo de máseres de OH en regiones de formación estelar realizado con el Very Long Baseline Array. Durante este proyecto observamos 41 regiones galácticas de alta y baja masa en las frecuencias principales de 1665 y 1667 MHz, así como en las líneas satelitales de 1612 y 1720 MHz. Estas últimas raramente se encuentran en regiones de formación estelar. De las 41 fuentes de la muestra, obtuvimos observaciones de alta resolución de las líneas satelitales en 14 fuentes: cinco (11%) mostraron lineas a 1612 MHz, y diez (23%) mostraron lineas a 1720 MHz. Creemos que existe una correlación entre la presencia de líneas satelitales y las regiones de formación estelar de alta masa.
A sample of all known giant radio sources (GRGs) has been compiled, from which a subset of sources has been selected for a detailed study of the environments of these sources by examining the distributions of galaxies in their vicinity using Sloan Digital Sky Survey (SDSS) III (DR9). We found that generally the giant radio sources do not occur in rich environments. Very few sources are in the richer environments but there is no significant signature for the asymmetric behaviour in these sources except in three giant radio sources J1021+1217, J1032+5644 and J1552+2005 (3C 326), the shorter arm is found to interact with a group of galaxies which forms part of a filamentary structure. In the case with strong and variable core, J0313+4120, the large flux density asymmetry is possibly also caused by the effects of relativistic motion.
RATIR es un telescopio robótico que tiene desde fines de 2012 operando en el OAN/SPM. COATLI será un nuevo telescopio robótico que se pondrá en marcha en el 2016 también en el OAN/SPM. Ambos tienen capacidades científicas únicas. RATIR permite realizar fotometría multibanda de objetos variables durante meses y años. COATLI permite obtener imágenes con una resolución de alrededor de 0.3 segundos de arco y con una cobertura amplia en el cielo. Los proyectos muestran que instrumentos innovadores permiten ciencia de punta.
30
Viernes

Ana María Martínez, candidata a la vicepresidencia de la AMC

Junio

La fricción gravitacional se define como la fuerza de frenado que siente un objeto masivo (perturbador) moviéndose a través de un medio de fondo, esto es, debido a la interacción gravitacional de este objeto con su estela inducida en el medio de fondo. Utilizando la teoría lineal de perturbaciones y un método semianalítico, evaluamos la fuerza de fricción gravitacional de un sistema binario suponiendo que su centro de masa se desplaza a velocidad constante en un medio gaseoso de densidad uniforme. Considerando además la velocidad de rotación de cada componente del sistema binario alrededor del centro de masas. Este trabajo es una generalización de lo realizado por Ostriker en 1999, quien derivó la expresiones analíticas para la densidad de la estela y la fuerza de fricción cuando el perturbador se mueve a velocidad constante en un medio gaseoso, y Kim y Kim en 2007, quienes evaluaron la fuerza de fricción cuando el perturbador se mueve en una órbita circular en un medio gaseoso. Obtuvimos la densidad de la estela que se genera y, conocida la densidad, se evaluó la fuerza de fricción dinámica numéricamente.
We utilize a suite of multiwavelength data, of 9 nearby spirals, to analyze the shock-induced star formation sequence, that may result from a constant spiral pattern speed. The sequence involves tracers as the HI, CO, 24um, and FUV, where the spiral arms were analyzed with Fourier techniques in order to obtain their azimuthal phases as a function of radius. It was found that only two of the objects, NGC 628 and NGC 5194, present coherent phases resembling the theoretical expectations, as indicated by the phase shifts of CO-24um. It was also found that the phase shifts are different for the two spiral arms. With the exception on NGC 3627, a two-dimensional Fourier analysis showed that the rest of the objects do not exhibit bi-symmetric spiral structures of stellar mass, i.e., grand design spirals. A phase order inversion indicates a corotation radius of ~95'' for NGC 628, and ~189'' for NGC 5194. For these two objects, the CO-Halpha phase shifts corroborate the CO-24um azimuthal offsets. Also for M51, the CO-70um, CO-140um, and CO-250um phase shifts indicate a corotation region.
We have explored the dynamical evolution of the comet 1P/Halley over 1 Myr with detailed numerical simulations, under the gravitational influence of all planets in the present day Solar System (except Mercury). To this purpose we employed the Mercury 6.2 code, including, in addition to the planets, the 9 biggest minor bodies (among them the known as dwarf planets but Sedna) to conduct the N-body simulation. Halley ́s comet fiduciary orbit, and a set of orbits surrounding it in phase-space (a-e), are solved as test particles in this problem. The ensemble of orbits explored is constructed as a mesh of 10,000 particles with different initial conditions covering the observational error of Halley’s orbit in semimajor axis and eccentricity (+- 10-6 AU and +- 10-6, respectively). We find that the comet’s fate is highly sensitive on initial conditions. Survival time maps from the simulations and Laskar frequency analysis maps for the vicinity of Halley’s comet are shown. Also, the maximum Lyapunov exponent for neighboring orbits is calculated. This shows that chaos is dominant for these highly eccentric bodies as found by Chirikov & Vecheslavov (1989) and produces large non-stable regions for the comet ́s surrounding phase space. We provide estimations of the probability of survival of the Halley ́s comet and a general perspective about the dynamical evolution of comets on a wider region of phase-space which covers several currently known Halley type comets.
El uso de la Estadística o Inferencia Bayesiana es cada vez más frecuente en diversas áreas de la astrofísica. Aún así, éste es un tópico que no suele ser incluido como parte de la formación de estudiantes de perorado y posgrado en física y astronomía. En esta charla expondré las bases del formalismo Bayesiano mediante su aplicación a un conjunto de problemas simples y fundamentales, útiles en diversas áreas de la astronomía. Enfatizaremos las ventajas que la Inferencia Bayesiana ofrece en el cálculo e interpretación de la probabilidad, en contraste con los métodos clásicos de la estadística frecuentista.
19

José María Torrelles, Instituto de Ciencias del Espacio (ICE-CSIC)

There is growing evidence provided by VLBI water maser observations suggesting that at the earliest stages of evolution of massive YSOsthere may exist short-lived (tens of years) episodic events associated with very poorly collimated outflows. This result is surprising since the current paradigm of star formation through accretion disks, and gas ejection via MHD mechanisms, does not predict outflows expanding without any preferential direction, but producing collimated outflows. From all the observed cases, the most singular is the one found in the high-mass star-forming region of W75N(B). In fact, in 1996, we detected a water maser shell of 0.1'' (130 AU) diameter around an unresolved (<0.1'') radio continuum source (VLA2). Monitoring this shell from 1996 to 2012, we find that it is expanding at ~ 30 km/s and, more importantly, that it has evolved from an almost circular shock-excited shell to an elliptical morphology of 0.28''x0.14'' size with a kinematic age of ~ 25 yr. In addition, the magnetic field around VLA2 seems to have also changed its orientation according to the new direction of the major axis of the shell. All these observations suggest that we are observing in "real time'’ the transition from a non-collimated, pulsed outflow event into a jet-like mass outflow during the first stages of evolution of a massive YSO. In this talk we will present all these results that could represent a major breakthrough in our knowledge of the formation and evolution of massive YSOs. We predict that VLA2 itself should have also evolved from a compact radio continuum source up to an elongated source, and with a spectral index consistent with a thermal radio jet. Very preliminary results of very recent (2014) sensitive and high angular resolution VLA observations of the radio continuum emission of VLA 2 will be briefly presented (Carrasco-Gonzalez et al. 2014). Possible scenarios to explain the origin of the initial non-collimated outflow are considered, although the origin of the transformation into a jet-outflow is still under study.

Julio

I will present recent results on the hierarchical gravitational fragmentation (HGF) of molecular clouds (MCs) leading to the formation of dense cores. I will first discuss the scenario of HGF as an alternative to the standard scenario of turbulent support --> turbulent dissipation --> collapse. In it, clouds are multi-Jeans-mass object undergoing global, multi-scale collapse, and the cores are the local centers of collapse. The lapse between the onset of local collapse and the formation of a singularity constitutes the prestellar phase. I will present numerical simulations of core growth during this phase in the idealized case of spherical geometry, immersed in a globally collapsing environment, discussing the evolution of the density and velocity profiles. I will also present synthetic molecular line observations of such idealized cores, aimed at determining to what extent such an idealized setup recovers the basic observational features of the cores, and which features require additional physics such as background turbulence and non-spherical symmetry.

Agosto

28

Bo Reipurth, Institute of Astronomy University of Hawaii

Septiembre

2
Martes

Yetli Rosas Guevara, ICC - Durham University

En esta plática voy a presentar la evolución de núcleos activos de galaxias (siglas en Inglés AGNs) en simulaciones cosmológicas. En particular, voy a hablar de simulaciones hidrodinámicas modernas diseñadas para producir un Universo virtual que reproduce las propiedades observadas de una población de galaxias, tal como la función de masa estelar de galaxias a z=0. La simulación engloba una región de 100 Mpc, resolviendo la formación de galaxias individuales con una resolución de 700 pc. La energía de feedback injectada por los agujeros negros es una parte clave de la simulación la cuál me enfocaré en esta plática. También mostraré la evolución de la función de luminosidad de los AGNs en bandas de rayos X así como otros resultados de la población de AGNs.
The Asymptotic Giant Branch stars (AGB) are evolved solar-type stars surrounded by a circumstellar envelope (CSE) composed of molecular gas and dust. The processed matter that gives rise to the CSE is expelled from the star towards the Interstellar Medium due to the stellar pulsation and accelerated by the pressure of stellar radiation on the dust grains. During most of the AGB phase, the envelope is considered spherically symmetric at large scales. However, there could be asymmetries at small scales probably related to the development at the end of this stage of the bipolar outflows observed in the proto-planetary nebulae. Hence, the observation and analysis of these asymmetries could throw some light on the formation of the outflows. IRC+10216 is one of the best known C-rich AGB stars because of its proximity (~120 pc) and chemical richness. This star, usually considered the archetypical AGB star, has developed a CSE with a dusty component elongated along the NE-SW direction in the plane of the sky. This elongation was observed at scales of 0.1-0.2" and 1" in the near- and mid-IR (e.g., Ridgway & Keady, 1988; Weigelt et al., 1998) evidencing the presence of a bipolar structure close to the central star. Regarding the molecular emission, only the brightness distributions of SiC2 and CN are elongated along the NE-SW and the perpendicular direction at scales of 20-40" while the emission of other molecules such as SiS, HCN, CS, HC3N, C3N is roughly spherically symmetric (Takano et al., 1992; Bieging & Tafalla, 1993; Gensheimer et al. 1995; Lucas et al., 1995). However, the molecular observations at scales smaller than 0.6" are very scarce and no molecular counterpart of the bipolar structure in the dusty component of the envelope has been found so far. In this talk, we will present new low spectral, high angular resolution molecular observations (HPBW>0.25") of SiS, H13CN, SiO, and SiC2 carried out with CARMA at 1.2 mm. These observations are analyzed in detail with a new version of the code developed by Fonfría et al. (2008) to model the continuum and molecular emission of spherically symmetric envelopes, improved to reproduce the 3D emission of asymmetric envelopes. The derived abundance distribution of H13CN, SiO, and SiC2 suggests the existence of three remarkable directions towards the NE, SSW, and SE between the stellar surface and ~50R* (~1") along which the abundance of these molecules (and the vibrational temperature in the case of SiO) are clearly different than for other directions in the plane of the sky. The SiS observations cannot be used to analyze these remarkable directions but they support the existence of maser emission in the observed line (v=0, J=14-13) proposed by Fonfría et al. (2006) and allow us to sketch the maser emitting structure located in the innermost envelope.
The gas in protoplanetary disks has to be dispersed to give rise to planetary systems. The final dispersion mechanisms remain debated. Photoevaporation by high-energy photons and the growth of planets itself are among the main candidates. In this talk, I will describe a result from an spin-off project of our young stellar object time monitoring campaign. Using our deeper radio images, we constrain some of the basic inputs of models of the dispersal of protoplanetary disks by photoevaporation. In particular, we set stringent upper limits to the extreme-UV photon luminosity, Phi_EUV < 1 to 4 x 10^41 s^-1, which lie at the lower end of what models need. Our results suggest that EUV photoevaporation likely is not the main agent in disk dispersal. Multiwavelength observations, including deeper radio images, can confirm this and test photoevaporation by X-rays.
En este seminario haré un breve resumen de una parte de mi actividad científica hasta la fecha. Aquélla comprende:
  • Calibración de estimadores de formación estelar usando modelos evolutivos de síntesis de población
  • Análisis de los estallidos de formación estelar en dos galaxias "starburst" locales emisoras de Lyman alfa
  • Emisión de rayos X de alta energía en galaxias "starburst"
  • Discernimiento de la formación estelar de la actividad nuclear en galaxias Seyfert 2 usando espectroscopía de rayos X

Octubre

We present the results of multifrequency observations of three large and asymmetric radio sources with the Giant Metrewave Radio Telescope (GMRT) and the Very Large Array (VLA). The radio luminosity of these sources are in the Fanaroff-Riley class II (FRII) range. These sources have diffuse lobes of emission, reminiscent of FRI radio sources, on one side of the galaxy although the opposite lobe has a hot-spot or peak of emission. We suggest the peak brightness asymmetries to be largely intrinsic in these Mpc-scale sources. Unlike in the case of lobes with hot-spots, the spectral index of the diffuse lobes remains largely similar with distance from the edge of the lobe, possibly due to reacceleration of particles in these diffuse lobes. This trend also suggests an intrinsic asymmetry in the lobes, rather than the hot-spots being invisible due to relativistic beaming effects. We also discuss the core radio spectra of these sources.
16

Enrique Vázquez, CRyA - UNAM

I will review recent theoretical work on the formation cold atomic and molecular clouds and their substructures -- filaments and dense clumps. At least under Solar Circle conditions, the convergence of large-scale gas streams in the diffuse medium, caused by either turbulent motions or larger-scale instabilities, may coherently trigger the production of large extents of cold gas through thermal instability. The clouds may thus quickly acquire masses much larger than their thermal Jeans mass, engaging in large-scale, nearly pressureless, gravitational contraction. Under these conditions, collapse proceeds along the shortest dimension first, sequentially forming filaments and then clumps. Gravitationally-formed filaments grow in mass until they become locally unstable, forming the clumps. The remainders of the filaments then accrete onto the clumps, because an elongated structure has a longer free-fall time than a spherical one. I review the basic analytic theoretical results concerning the radial structure of filamentary structures in hydrostatic equilibrium, and extensions to collapsing and accreting cases.

The clumps themselves grow in mass in such a way that their early, pre-stellar stages resemble Bonnor-Ebert spheres. Clumps formed by this mechanism appear nearly virialized, but the nonthermal motions in this case do not represent true turbulent, random motions, but instead are dominated by infall, superposed on a moderately turbulent background. Clumps appearing as "unbound" of "pressure-confined" may actually be the result of an underestimation of the relevant gravitational mass.

In this scenario, a low star formation efficiency can be maintained because stellar feedback is capable of shutting off local star formation events after roughly 10% of the local gas mass has been converted into stars, at least for low- to intermediate-mass clouds. To conclude, I will by briefly compare this scenario with the alternative view of clouds in approximate virial equilibrium, controlled by supersonic turbulence.
I will present an observational project aimed at studying the fragmentation of massive dense cores, which constitute the first stages of cluster formation and the cradles where high-mass stars are born. The project is based on a sample of 19 protoclusters with luminosities spanning three orders of magnitude, and which were observed in the millimeter range down to mass sensitivities (~0.3 Msun) and spatial resolutions (~1000 AU) comparable to infrared/optical studies of clusters. Among the 19 regions, 30% show no signs of fragmentation, while 50% split up into >~ 4 millimeter sources. We inferred the density structure of the 19 cores through a simultaneous fit of the submillimeter radial intensity profiles and the spectral energy distribution, and find a possible trend of fragmentation increasing with density within a given radius. We also studied the relation between turbulence and fragmentation level and find that gravity, rather than turbulence, seems to be a key ingredient in determining the fragmentation level of massive dense cores. Finally, I will present independent very recent results of different fragmentation levels in two massive cores of the infrared dark cloud G14.225−0.506, which again suggest that gravity is regulating the fragmentation process in this cloud.
30

Ruben Krasnopolsky, Academia Sinica, Institute of Astronomy and Astrophysics

The formation of a rotationally supported disk is a crucial event of star formation, both currently and likely in the early Universe. This circumstellar disk is the place where planets form. I would like to draw attention to a fundamental difficulty with circumstellar disk formation in the presence of magnetic fields, and review possible solutions of this difficulty based on state of the art numerical simulations.

It had been expected that a disk would form automatically out of the collapse of rotating cores because of angular momentum conservation. However, this simple explanation is not guaranteed to work, because magnetic braking and magnetic instabilities can oppose disk formation, in the presence of the observed level of magnetic fields in star-forming regions of our local universe. Indeed, in the simplest case of ideal MHD in axisymmetry, analytic and numerical work showed that disk formation is completely suppressed by excessive magnetic braking of rotation --- leaving insufficient angular momentum to form a disk.

Nevertheless, protostellar disks are commonly observed, and some of them are large. Based on our numerical simulation work, I will discuss in particular three of the suggested resolutions of this problem: diffusion, asymmetry, and turbulent waves.

Direct magnetic diffusion, such as Ohmic dissipation and the Hall effect, needs to reach very large values to be able to form large disks. Enhanced diffusive effects such as turbulent reconnection diffusion can be of great help in decoupling mass from magnetic flux.

Both turbulence (in the form of waves) and asymmetry (in the form of misalignment between magnetic field and rotation) have been shown to form strongly warped, highly asymmetric infalling structures feeding the disk with matter and angular momentum. In our simulations, this warping helps to decouple mass from magnetic flux, and it also decreases the angular momentum removal due to magnetic torques and magnetized outflows. Together, both beneficial effects of warping enable the formation of a rotationally supported disk.

Noviembre

13

Grant Tremblay, Yale University

In this presentation I will discuss a relatively unexplored connection between LCDM structure formation scenario and the evolution of binary supermassive black holes, and how this connection can be exploited in observations and theory. I will also review the value of selfconsistently producing the formation of a Mily Way like galaxy system inside a cosmological galaxy formation simulation. I will present one of the newest efforts designed to be a laboratory for galactic astronomy and its potential for constraining the history of MW Super Massive Black Hole.
Se presenta el proyecto del Servicio de Clima Espacial-Mexico (SCIESMEX). El SCIESMEX es un proyecto aprobado por la convocatoria de Cátedras de Jóvenes investigadores de CONACyT para desarrollarse en la Unidad Michoacán del IGEF (IGUM). Se explica la motivación: ¿qué es el clima espacial? ¿por qué necesitamos estudiar el clima espacial en México? ¿qué dice la nueva ley de protección civil? ¿cuál es el contexto nacional e internacional del proyecto? ¿cómo se relaciona con el plan de desarrollo del IGEF y de la Agencia Espacial Mexicana (AEM)? El SCIESMEX forma parte de los servicios geofísicos que brinda el IGEF a la nación (SSN, SMN, Servicio Magnético), y va a operar dentro una coordinación internacional de servicios de clima espacial (ISES), conformandose como un 'Warning Regional Center' (WRC) del ISES. Vamos a explicar la operación y fortalecimiento de la red de instrumentos de clima espacial de la UNAM, la adquisición, resguardo y acceso de sus datos, retomando el proyecto del VESO para hacerlo un verdadero observatorio virtual (Repositorio Nacional de Datos de Clima Espacial). Explicaremos también cómo funciona el servidor del SCIESMEX y su operación en redes sociales, como una aplicación de datos de clima espacial en tiempo real, responsable de emitir las alertas regionales de eventos solares potencialmente riesgosos en términos de clima espacial. Finalmente anunciaremos e invitaremos a la conferencia de clima espacial y observaciones remotas de la heliosfera interna que se va a desarrollar en Morelia en octubre de 2015.

Diciembre

2
Martes

Carlos Román, IA-UNAM Ensenada

4

Johannes Schmid-Burgk, Max-Planck-Institut fuer Radioastronomie (MPIfR)

After a quick reminder of the history of detecting molecules in space and of the main channels of molecule formation I will select a few examples to demonstrate the use of the cosmic chemical laboratory in determining basic properties of matter that could not be obtained otherwise, and of some applications to the processes of star formation. Special attention will be given to the water molecule, both to its physics and its appearance in space. Then the astro search for ever larger molecules will be discussed with a view on the presence and origin of prebiotic cosmic substances such as the ones recently discovered at the Max Planck Institute of Radio Astronomy in Bonn.