Searching for the formation mechanisms of brown dwarfs
Speaker: de Gregorio Monsalvo, Itziar
Filiation: ESO Chile
Date: March, 25th 2021
New generation of Submillimeter facilities in the North of Chile, like the APEX antenna and the Atacama Large Millimeter/submillimeter Array (ALMA), offers for the first time the possibility for studying the formation of stars, brown dwarfs, and planets with unprecedented sensitivity and angular resolution in the millimeter/submillimeter regime. The formation of Brown Dwarfs (BDs) is a debated topic of research. The most widely discussed scenarios for the formation of BDs include turbulent fragmentation, disk fragmentation and subsequent ejection, photo-evaporation of massive pre-stellar cores and ejection from multiple protostellar systems. In the last decade the presence of circumstellar disks around BDs, as well as jets, herbig haro objects, outflows, and accretion have been identified. ALMA observations helped to characterize the properties of the dust and gas disks surrounding these objects, constraining their masses and radii, and revealing the presence of grain growth to mm-grain sizes in the disk, which suggests the potential of finding rocky planets surrounding BDs. In the most recent works the presence of resolved cavities around BDs and very low mass stars has made these objects good laboratories to study disk evolution and planet formation. For more than a decade our team made an effort to shed light into the different formation mechanisms of these substellar objects using a multi-wavelength and a multi-technique approach, where ALMA has played a key role. In this talk I will provide an overview on these studies that involves observations from optical to centimeter wavelengths and the different strategies applied to search for the best pre- and proto-BDs candidates in various molecular clouds.
Multiple stellar populations in globular and massive star clusters: Properties, origin, open questions
Speaker: Charbonnel, Corinne
Filiation: Université de Genève
Date: March, 4th 2021
Globular clusters (GCs) are fascinating objects nearly as old as the Universe that provide insight on a large variety of astrophysical and cosmological processes. However, their formation and their early dynamical evolution are far from being understood. In particular, the classical paradigm describing GCs as large systems of coeval stars formed out of chemically homogeneous material has been definitively swept away by recent high-precision spectroscopic and deep photometric observations. These data have provided undisputed evidence that GCs host multiple stellar populations, with very peculiar chemical properties. Evidence is also accumulating about the presence of multiple stellar populations in young massive star clusters in Local Group galaxies. In this talk, I will review the properties of these multiple populations, before presenting the different scenarios that have been proposed to explain their formation. I will focus on the (many) current theoretical issues and on the possible relationships between GCs and young massive star clusters observed in the local universe. I will conclude on open questions.
The influence of the star-forming environment on planetary systems
Speaker: Parker, Richard
Filiation: The University of Sheffield
Date: February, 11th 2021
Planet formation occurs at the same time as star formation, and so the environments in which stars are born are also the birthplaces of planetary systems. Star forming regions are very dense, meaning that encounters between stars and planetary systems are common. Furthermore, the intense UV radiations fields from intermediate and massive stars can truncate, or destroy protoplanetary discs. In this talk, I will describe the detrimental effects of interactions and photoevaporation on young planetary systems. I will then finish by highlighting two positive effects of the star-forming environment on planetary systems; short-lived radioisotopes and enlargement of habitable zones in binary star systems.
Vera C. Rubin Observatory: A Big Data Machine for the 21st Century
Speaker: Rawls, Meredith
Filiation: Washington University
Date: January, 28th 2021
The Vera Rubin Observatory (former LSST) will be a transformative instrument for all of astrophysics, from cosmology to star formation. This talk will cover its operations and science with a particular view on Big Data.
Osiris-Rex: results on a mission to understand planetary systems
Speaker: de León, Julia
Filiation: Instituto de Astrofísica de Canarias, Spain
Date: January, 21st 2021
In September 2016, the NASA OSIRIS-REx spacecraft was successfully launched from Cape Canaveral Air Force Station, in Florida. That was the beginning of an amazing journey to reach near-Earth asteroid Bennu, collect a sample of material from its surface, and bring it back to Earth in 2023. The so-called “Touch-And-Go” maneuver or TAG, took place on October 20, 2020 and the sample collector head has been safely placed into the Sample Return Capsule. Images obtained from a series of cameras on-board the spacecraft show that the collector head is holding much more than 60 g of material (the mission’s minimum requirement). Bennu is a primitive, carbon-rich asteroid, containing organic and water-bearing minerals like clays. These type of asteroids have not significantly changed since they formed nearly 4.5 billion years ago, and therefore are considered relics from the early stages of our Solar system. The OSIRIS-REx mission will bring for the first time pristine material from such early epoch, that will be analyzed in the laboratory and will help scientists to confirm if asteroids are a source of the water and organic molecules that may have made their way to Earth and other planetary bodies early in their histories. In addition, Bennu is one of the most potentially hazardous asteroid (PHA), coming close to Earth every six years. OSIRIS-REx mission spent two years orbiting and studying in detail the surface of this extremely interesting asteroid. I will go through the main findings provided by the data obtained with the instruments on-board the spacecraft, including the discovery of a rough, rocky surface, the unexpected particle ejection events, or a collection of bright, silicate-rich boulder having an exogenous origin.
The Blanco DECam Bulge Survey: A Panchromatic Window the Galactic Bulge
Speaker: Rich, Michael
Filiation: UCLA, Department of Physics and Astronomy
Date: January, 14th 2021
The development of wide field imaging cameras on large optical telescopes has opened a new opportunity to examine stellar populations over the full optical/near-IR passband. We have used the Dark Energy Camera on the Blanco 4m telescope to image 200 sq. deg of the Galactic bulge in the Rubin/LSST passbands of ugrizY. The use of the u band permits calibration of red clump star metallicities to a precision of ~0.2 dex, and the use of the u band to observe and study multiple populations in many of the globular clusters in the field of regard. We show that some claims for extremely young stellar populations in the Galactic bulge cannot be supported. We also find that the bulge divides into two abundance distributions- one close to the one-zone model of chemical evolution near the Galactic plane, and the other a more metal poor distribution, outside of 500 pc. We also find that the structure of the bulge as a function of metallicity is stratified parallel to the plane and previous claims for a spheroidal distribution for [Fe/H]<0 are not sustained. We will discuss the future science being undertaken as our sample is integrated with Gaia astrometry. I will discuss the implications for the formation history of the bulge.
Primordial black holes, gravitational waves and dark matter
Speaker: García-Bellido, Juan
Filiation: IFT (UAM-CSIC)
Date: January, 12th 2021
More than twenty years ago, we predicted that massive primordial black holes (PBH) would form via the gravitational collapse of radiation and matter associated with high peaks in the spectrum of curvature fluctuations, and that they could constitute all of the dark matter (DM) today. In 2015, we predicted the clustering and broad mass distribution of PBH, which peaks at several Msun, and whose high-mass tails could be responsible for the seeds of all galaxies. Since then, AdvLIGO/Virgo interferometers have detected gravitational waves from at least fifty merger events of very massive and spin-less black hole binaries, and we propose that they are all PBH. We have recently understood that a universal mechanism associated with rapid changes in the number of relativistic species in the early universe could have been responsible for the formation of PBH at specific scales and thus have a very concrete prediction for the mass spectrum of DM-PBH, with broad peaks at 10^{-5}, 2, 80, and 10^6 Msun. In particular, the QCD quark-hadron transition could be responsible for the efficient production of baryons over antibaryons at PBH collapse, thus explaining the presence of baryons today and the relative abundance of DM. We predict that within a few years a less than one solar mass PBH will be detected by AdvLIGO/Virgo, and that an array of GW detectors could be used to determine the mass and spin distribution of PBH dark matter with 10% accuracy. Thus, gravitational wave astronomy could be responsible for a new paradigm shift in the understanding of the nature of dark matter and galaxy formation.
On the formation of stellar clusters
Speaker: Moraux, Estelle
Filiation: Institut de Planétologie et d'Astrophysique de Grenoble
Date: December, 17th 2020
In this presentation, I will show how the analysis of the spatial distribution of young stars (YSO) and its comparison to the core population can reveal stellar formation episodes in star forming regions, and help us understand the fragmentation process. I will focus in particular on two very different regions: the relatively massive cluster NGC2264 and the Taurus association. Our recent study of the clump and YSO populations in NGC 2264 suggests a sequential star formation, starting from the northern part to the southern subregion. We propose also that the observed mass segregation in the central part is inherited from that of clumps, itself resulting from a dynamical scenario of star formation. In contrast, the Taurus association is much less dense and dynamic, which allowed us to identify pristine small scale stellar structures, called NESTs, that correspond to the preferred sites of star formation. The analysis of their properties indicates two distinct regimes which may correspond to the fragmentation of a single core or a group of cores. In addition, a further study at even smaller scale argue for a cascade fragmentation scenario. I will then finish by presenting the public sofware called S2D2 that we developed in the framework of the StarFormMapper project for the community to look for NESTs in star forming regions.
Stellar population gradients and kinematics of ETGs as revealed by MaNGA
Speaker: Domínguez Sánchez, Helena
Filiation: Instituto de Ciencias del Espacio, CSIC
Date: December, 10th 2020
In this talk I will summarise the findings presented in a series of four papers dedicated to the study of early type galaxies (ETGs) with integral field spectroscopy (IFU) from the MaNGA survey. The formation channels and mass assembly of ETGs is still a matter of debate in current galaxy evolution models. The combined analysis of galaxy kinematics and stellar population gradients (age, metallicity, alpha-enhancement, initial mass function -IMF-) is a powerful tool to disentangle between in situ star formation or merger events. We divide our sample into elliptical fast rotators (E-FR), elliptical slow rotators (E-SR) and lenticular (S0). To achieve enough signal to noise to reliably measure IMF variations, we need to stack the galaxies in bins of luminosity and central velocity dispersion. We observe significant differences between the three sub-samples — e.g., E-FR are much younger and metal rich than E-SR — , suggesting that kinematics and morphology have a strong impact on galaxy content. In addition, I will show that there are three mass-scales where scaling relations change slope and for which there is a dramatic change in the number counts and stellar population gradients of ETGs. I will also discuss the implications of IMF variations within galaxies and how this helps reconciling stellar mass with dynamical mass estimates. Finally, I will show that the thickness of the Fundamental Plane depends strongly on morphology. If the sample only includes E-SRs, then the observed scatter is significantly reduced.
Flaring on the Sun at all scales
Speaker: Harra, Louise
Filiation: PMOD/WRC Davos, ETH-Zürich, Switzerland
Date: November, 19th 2020
The Sun shows activity across a wide range of size and energy scales. We shall take a journey from the smallest scale events to the largest energy releases in the solar system. The energy release is due to the magnetic fields on the Sun and how they interact. Using EUV/UV spectroscopy different layers of the solar atmosphere can be probed in order to understand the physical processes that occur. The EUV imaging spectrometer onboard the Hinode spacecraft has been operating for 13 years with an extensive datasets. The NASA IRIS mission was launched in 2013 and provides data in the UV. In 2020 the Solar Orbiter mission has been launched providing a third spectrometer probing the solar atmosphere. We will discuss future science goals in the coming years.
GRAVITY+, all Sky, High Contrast, Milli-Arcsecond Optical Interferometric Imaging and Spectroscopy
Speaker: Eisenhauer, Frank
Filiation: MPE
Date: November, 12th 2020
GRAVITY+ will be the next generation interferometric instrument for the ESO VLT Interferometer. It will be the successor of the extremely successful GRAVITY, which has resulted in breakthrough observations of objects such as massive black holes and exoplanets. The GRAVITY+ project will upgrade GRAVITY and the VLTI in order to open up the extragalactic sky for milli-arcsecond resolution interferometric imaging, and give access to targets as faint as K = 22 mag. GRAVITY+ will measure the black hole masses of active galactic nuclei across cosmic time, and obtain high quality exoplanet spectra and orbits. Following a summer 2020 recommendation by ESO’s STC, GRAVITY+ is entering a phase A process in order to become ESO’s next VLT facility instrument.
The Arecibo Observatory Roadmap for the Future: science enhancement plans under UCF management.
Speaker: Pinilla-Alonso, Noemi
Filiation: Florida Space Institute and Arecibo Observatory, UCF. Miami, USA
Date: November, 5th 2020
The Arecibo Observatory (AO) has supported cutting-edge research in the fields of Astronomy, Planetary Science, and Space Atmospheric Science for decades. The unprecedented sensitivity of the Arecibo antenna has led to fundamental contributions in a wide variety of research programs, including the first detection of an exoplanet around pulsar (Wolszczan & Frail 1992), indirect detection of gravitational waves (GWs) that resulted in the 1993 Nobel Prize in Physics (Hulse 1994), and discovery and localization of a repeating Fast Radio Burst (Spitler et al. 2016, Marcote et al. 2016). In 2020, AO will publish its roadmap for the next decade. This document will exist as a reference, but living, document containing our vision for the future capabilities of the observatory. It will also aim to inspire the users community to open new paths for future science drivers. In this colloquium, I will discuss the science and technical roadmap in the short term and how we plan to enhance AO.s science return, with the goal of opening new and fruitful international collaborations.
The black hole at the Center of the Milky Way
Speaker: Ghez, Andrea
Filiation: UCLA, Department of Physics and Astornomy
Date: October, 29th 2020
The massive black hole at the center of the Milky Way is the nearest such object. Observations of stellar orbits have accumulated firm evidence for its nature and are being used now to test predictions of General Relativity. The observational work on Sagittarius A* by Andrea Ghez has just been awarded with the Nobel Prize for Physics 2020.
The star formation process on cloud-scales in nearby galaxies
Speaker: Schinnerer, Eva
Filiation: Max-Planck-Institut für Astronomie
Date: October, 15th 2020
Where do stars form and how is their formation regulated across galactic disks are two critical questions for our understanding of the star formation process. High angular observations of nearby galaxies allow us to sample the star formation process across entire galactic disks reaching now regularly the scales of the star-forming units, namely Giant Molecular Clouds (GMCs) and HII regions. Such data provide new insights on the molecular gas reservoir and its role in the star formation process as well as information on the importance of galactic components such as bulges, stellar bars, spiral arms and active galactic nuclei (AGN) in the conversion of cold (molecular) gas into stars. I will introduce the PHANGS (Physics at High Angular resolution in Nearby GalaxieS) survey and present a few highlights from the ongoing research of the collaborations.
Recent findings on nova explosions
Speaker: Toalá Sanz, Jesús Alberto
Filiation: Instituto de Radioastronomía y Astrofísica, IRyA-UNAM, Morelia, Mexico
Date: October, 8th 2020
Nova events are the result of the interaction of low-mass binary systems. A compact white dwarf (WD) accretes material from an old and cold companion until a thermonuclear runaway takes place on its surface. Such explosive events can be considered the scaled-down siblings of supernova (SN) explosions, but its study has many advantages over SNe, as nova events are more numerous (some systems even exhibit recurrent explosions within decades) and their evolution and expansion can be followed in human time-scales. In this talk I will review the most recent findings of our group. I will present a multi-epoch study of a sample of novae from historical archival observations in conjunction with recent ground-based images to characterize the hydrodynamic evolution of nova shells. Finally, I will address our discovery of the first magnetized jet in a classical nova using Chandra and XMM-Newton X-ray observations.
Following black hole evolution from z=5: mergers and outflows
Speaker: Netzer, Hagai
Filiation: School of Physics and Astronomy, Tel Aviv University
Date: October, 1st 2020
The growth and evolution of the most massive black holes, and their host galaxies, can be followed from z=7 and even earlier. The critical events that shape this evolution are major mergers, Eddington or super-Eddington accretion, violent star formation, and powerful outflows. I will present the results of a systematic study of 40 AGN at z~4.8 using Gemini, VLT, Herschel and ALMA. Our recent (2019) ALMA data allow a fresh look at major mergers and their association, if any, with the most violent star formation in the early universe. I will also make a connection with our recent study of ionized AGN-driven outflows at lower redshifts and try to assess their efficiency in quenching star formation.
J-PAS: First light results of the JPCam
Speaker: Bonoli, Silvia
Filiation: Donostia International Physics Center (DIPC), Spain
Date: September, 17th 2020
The Javalambre-Physics of the Acclerating Universe Asptrohysical Survey (J-PAS) have just started to scan thousands of square degrees of the northern sky with 56 narrow band filters and the JPCam instrument with the telescope 2.5m of the Javalambre Observatory. Before the JPCam started its operation, we have observed with the pathfinder camera one sq. deg on the AEGIS field (along the extended Groth Strip). This colloquium will present the results of the first light of the JPCam, and will show the potential of J-PAS through the analysis of the pathfinder mini-JPAS survey. This data were already public delivered in December 2019, and the paper with presentation of the first results (Bonoli et al 2020) submitted to A&A.
Massive black hole binaries in the cosmos
Speaker: Volonteri, Marta
Filiation: Institut d'Astrophysique de Paris
Date: September, 10th 2020
Massive black holes weighing from a few thousands to tens of billions of solar masses inhabit the centers of today's galaxies, including our own Milky Way. Massive black holes also shone as quasars in the past, with the earliest detected a mere one billion years after the Big Bang. Along cosmic time, encounters between galaxies hosting massive black holes in their centers have produced binary massive black holes that eventually coalesced by emission of gravitational waves. I will discuss the physical processes through which massive black holes pair and bind, present the analysis of cosmological simulations to investigate the properties of merging massive black holes and their host galaxies and conclude with how we can use gravitational wave observations with ESA's planned satellite LISA to constrain the evolving population of massive black holes.
Active Galactic Nuclei: fueling and feedback
Speaker: Combes, Françoise
Filiation: Observatoire de Paris
Date: September, 3rd 2020
Dynamical mechanisms are essential to exchange angular momentum in galaxies, drive the gas to the center, and fuel the central super-massive black holes. While at 100pc scale, the gas is sometimes stalled in nuclear rings, recent observations reaching 10pc scale, or 60mas with ALMA, have revealed, within the sphere of influence of the black hole, smoking gun evidence of fueling. Observations of AGN feedback will be described, together with the suspected responsible mechanisms. Molecular outflows are frequently detected in active galaxies with ALMA and NOEMA, with loading factors between 1 and 5. When driven by AGN with escape velocity, these outflows are therefore a clear way to moderate or suppress star formation. Molecular disks, or tori, are detected at 10pc-scale, kinematically decoupled from their host disk, with random orientation. They can be used to measure the black hole mass.
The Orion Radio All-Stars: new insights into YSO radio emission, using the VLA, VLBA, and ALMA
Speaker: Forbrich, Jan
Filiation: University of Hertfordshire
Date: July, 30th 2020
With significant new observing capabilities, centimeter-wavelength radio astronomy is currently in a renaissance leading up to the advent of the Square Kilometre Array (SKA), highlighting new opportunities and also technical challenges. The sensitivity upgrades of both the NRAO Very Large Array (VLA) and the Very Long Baseline Array (VLBA) have begun to provide us with a much improved perspective on stellar centimeter radio emission, particularly concerning young stellar objects (YSOs) and ultracool dwarfs. For the first time we now have systematic access to the radio time domain and new information to disentangle thermal and nonthermal emission. I will mainly present the Orion Radio All-Stars, an ongoing project targeting the Orion Nebula Cluster (ONC) with the VLA, VLBA, and ALMA. With simultaneous radio-X-ray time domain information (Chandra), this project is providing first constraints on YSO radio flares and their relation with X-ray flares, as well as improved constraints on the overall high-energy irradiation of their surroundings, including protoplanetary disks. Our astrometric follow-up of all identified VLA targets in Orion is the largest VLBA survey for YSO emission to date. Other than providing a nonthermal census, I will additionally discuss the use of the VLBA for precision stellar astrometry in the Gaia era. I will conclude with a first look at variable millimeter continuum emission in the inner ONC, targeting synchrotron flares in this new window on high-energy processes in YSOs.
Young Runaway Stars
Speaker: Rodríguez, Luis Felipe
Filiation: Instituto de Radioastronomía y Astrofísica, UNAM, México
Date: February, 20th 2020
Most stars have spatial velocities within a few km/s of the average velocity of their surroundings and can be considered to be gravitationally trapped. There are, however, a small number of stars that move at velocities of tens or even hundreds of km/s with respect to their environment and that will eventually escape from there. The archetypal runaway stars are mu Col and AE Aur that escaped in opposite directions from the vicinity of the Orion Nebula Cluster about 2.5 million years ago at velocities of order 100 km/s. Can we find “young” (i. e. recently ejected) runaway stars in regions of star formation? We will present the cases of an O6 star that was ejected about 6,000 years ago from the Welch ring of ultracompact HII regions in W51N and review the case of the BN/KL region in Orion from where six runaways ejected only 500 years ago have been detected. Finally, we will discuss the mechanisms that have been proposed to produce runaway stars.
Extrasolar planets: recent advances and future challenges
Speaker: Cabrera, Juan
Filiation: DLR Berlin
Date: February, 4th 2020
Recently a group of scientists has confirmed the presence of water in the atmosphere of a super Earth orbiting in the habitable zone of its host star. But what what does this milestone represent in the search for life outside Earth? What do we mean by habitable? What do we really know about extrasolar planets, their internal structure or origins? What is a super Earth, the most common planet category know to date for which no example is found in our solar system? How do we characterize exoplanetary atmospheres? How are these different from the planetary atmospheres in our solar system? How do we search for life? In my talk I will present an overview of recent discoveries in the field of extrasolar planet characterization with focus on their atmospheres, habitability, and the search for life. I will take the opportunity to introduce the most recent European space missions related to planet characterization: CHEOPS, PLATO, and ARIEL.
Extragalactic survey science in the 2020s: the role of radio continuum observations with the SKA
Speaker: Sargent, Mark T.
Filiation: U. of Sussex, Dept. of Physics and Astronomy, Astronomy Centre (UK)
Date: January, 23rd 2020
Extragalactic surveys in the 2020s will reveal the full diversity of the galaxy assembly process: from environment-dependent evolution to the build-up of mass inside galaxies, and with a complete accounting of all relevant processes/constituents ensured by multi-wavelength coverage. Observations at radio wavelengths carry a unique potential in that they can probe star-formation activity and cold gas content, i.e. place constraints on both galaxy growth rates and the fuel for future galaxy growth. With the construction of the Square Kilometre Array (SKA), radio astronomy will enter a new era; high-sensitivity, high-resolution and dust-unbiased radio imaging will provide a confusion-free census of star formation and black hole activity, regardless of whether these occur in dust-obscured or optically thin regions. I will review the high-priority science cases developed by the SKA Extragalactic Continuum Science Working Group and outline the challenges brought about by our still only partial understanding of some of the astrophysical mechanisms producing radio emission (e.g. the relation between star formation rate and radio continuum luminosity). Thanks to an order of magnitude increase in survey speed compared to existing radio telescopes, SKA surveys will detect millions of galaxies. I will summarize how - in addition to advancing our understanding of the drivers of the cosmic star-formation history - "commensal" survey design will ensure that information on galaxy shapes, redshifts, spatial distribution and polarization can be used for cosmological studies and to trace the evolution of magnetic fields in galaxies and the cosmic web.
Unveiling the nature of planetary systems
Speaker: Pozuelos, Francisco J.
Filiation: Space Sciences, Technologies and Astrophysics Research (STAR) Institute, Université de Liège, Liège, Belgium
Date: December, 10th 2019
The burgeoning field of exoplanets has yielded thousands of discoveries, which collectively have the potential to help us better understand our place in the Universe. Every month more and more planetary systems are being discovered, some of them in highly exotic configurations never observed previously. The combination of different techniques and studies are needed to unveil the real nature of these planetary systems. In this seminar, I will review some of the most recent photometric surveys notably dedicated to find Earth-size planets, such as TESS and SPECULOOS, and how the combination of their findings with ground-based spectroscopic surveys, such as CARMENES, can be used to discriminate between families of planets: rocky super-Earths, volatile-rich super-Earths, Neptunes etc. I will also show how dynamical simulations help to better understand the planetary architecture of each system discovered by the aforementioned methods. Indeed, as it happens with studies of our own Solar System, to yield a deeper understanding of planetary architectures, both in general and specific cases, we need to study each system as a whole by taking into consideration the star, the planets, and the minor bodies within the system (dust disks, main asteroid analogues, etc.). I will show how the combination of all these methods (photometry, spectroscopy, and dynamical simulations) is necessary to shed light onto the real nature of a given planetary system.
Recent advances about the exoplanetary exospheres
Speaker: García Muñoz, Antonio
Filiation: Technical University of Berlin and DLR
Date: November, 27th - 28th 2019
The upper atmosphere of a planet plays a key role at protecting the lower altitudes from the effects of energetic stellar EUV and soft X-ray photons and keV-energy precipitating particles. Through a variety of transport processes, the upper atmosphere also participates in the net loss of a planet’s bulk composition into space. As such, the physics and chemistry occurring in the upper atmosphere influence the evolution of a planet over its lifetime. Understanding these processes is critical to form a complete picture of planet evolution and their response to the stellar environment. Exoplanets represent a unique opportunity to advance our understanding of upper atmospheres because of the diversity of conditions they are exposed to. In this seminar, I will give an overview on recent advances in the investigation of the upper atmospheres of exoplanets, both observational and theoretical.
Outflows and their feedback effect in galaxies
Speaker: Maiolino, Roberto
Filiation: Kavli Institute for Cosmology, University of Cambridge
Date: November, 14th 2019
Galactic outflows are an essential component of galaxies' lifecycle. They regulate star formation and can even totally quench star formation in galaxies, hence transforming star forming galaxies into passive systems. I will review the properties of galactic outflows, their multi-phase nature, their driving mechanism, both in normal star forming galaxies and in galaxies hosting Active Galactic Nuclei, both in the local Universe and in primeval galaxies. I will show that the "ejective" mode is less effective than previously thought in quenching star formation in galaxies, in the sense that outflows are generally not really capable of cleaning galaxies of their gas content. However, outflows can contribute to heat their circumgalactic medium hence suppressing accretion of fresh gas, and therefore quenching galaxies as a consequence of "starvation". I will also show that, although galactic outflows are generally associated to negative feedback, they can also have a positive feedback effect, in the sense that they can also foster star formation. In particular, I will show recent evidences of star formation occurring inside galactic outflows. This phenomenon was predicted by recent models and could provide a new channel for the formation of the spheroidal component of galaxies.
Characterization of (exo)Planetary Atmospheres
Speaker: Molaverdikhani, Karan
Filiation: Heidelberg University/MPIA, Germany
Date: November, 11th - 15th 2019
Characterization of planetary atmospheres has always been a challenge. While the next generation of facilities, such as ELT, JWST, and ARIEL, will improve our understanding of planetary atmospheres, the number of well-characterized exoplanet atmospheres is expected to remain limited. Large-scale simulations assist us with this shortcoming by predicting the diversity of the planetary atmospheres, connecting the spare observational measurements, and by pointing toward the regions on the parameter space where a higher chance of the detection of planets with desired properties is expected. I will overview our current understanding of planetary atmospheres and will highlight the results of our hierarchical modelling of planetary atmospheres; including our newly proposed classification scheme for irradiated gaseous planets, the Methane Valley, and a sweet-spot to study disequilibrium chemistry by JWST.
Neutral and molecular gas outflows as tracers of the impact of radio jets
Speaker: Morganti, Raffaella
Filiation: Netherlands Institute for Radio Astronomy
Date: October, 31st 2019
Our view of the gas and its physical conditions in the central region of AGN has been enriched by the discover of fast and massive outflows of HI and molecular gas. These outflows can be driven by radiation/winds but also by the interaction of the radio plasma with the ISM. Understanding the origin and quantifying their impact requires to trace their location and derive their physical conditions (density of the gas, mass, mass outflow rate and kinetic energy of the outflow etc.). Particularly interesting has been the finding that in the first phase of their life, jet in radio galaxies can be particularly effective in driving such outflows. This crucial phase is at the heart of the idea of feedback, therefore particularly relevant for studying feedback in action. In this talk, I will present some of the results we have obtained to trace jet-driven HI and molecular gas outflows down to scales ranging from hundred to tens of pc. The impact of low-power radio jets will be discussed and the comparison with the predictions from numerical simulations will also be presented. Outflows of up to few hundred Msun/yr have been found in molecular gas using ALMA while the HI observed with VLBI is showing that the outflowing gas is clumpy as also predicted from numerical simulations. I will describe the kinematics of the gas and its conditions and the relevance they may have for feedback.
Molecular spectroscopy at high resolution for everyone
Speaker: Martín Ruiz, Sergio
Filiation: European Southern Observatory - Joint ALMA Observatory, Chile
Date: October, 23rd 2019
Molecular observations at high resolution is being revolutionized by the success of ALMA and the upcoming advent of SKA. In this talk I will explain the recent progress in the field of molecular observations in the central regions of galaxies and the big steps that we are currently making in the use and understanding of molecular tracers as a proxy to buried physical processes in active galaxies. I will show some preliminary results from the ALCHEMI ALMA Large Program aimed at imaging at unprecedented resolution and sensitivity the chemical complexity within central molecular zone of the prototypical starburst NGC 253. I will try to sneak peak its astrochemical value but also to link this study to the understanding of physical properties in distant heavily obscured galaxies as well as those of the center of our Galaxy. I will aim at showing the potential of molecular studies in a variety of astrophysical objects from local galaxies, to high-z, and/or transient energetic events like GRBs. Not only instruments like ALMA are aiming at becoming accessible to not experts in interferometry but also software tools need to play the same role. I will present the software package MADCUBA that allows to easily analyze complex molecular spectra from state of the art instruments.
What's is the metallicity of cool dwarf stars?
Speaker: Rojas-Ayala, Barbara
Filiation: Universidad Andrés Bello, Chile
Date: October, 17th 2019
Cool dwarfs are the most numerous stars in the Galaxy and they account for most of its baryonic mass. However, they are likely the least understood main sequence stars. Their complex atmospheres, due to their low temperatures and high surface gravities, have made their spectroscopic study a hard task. Until recently, their basic physical properties, such as radii and mass, were poorly constrained due to the lack of empirical data. Stellar theoretical models were also affected by this and had relied on incomplete or approximate input physics to predict their main characteristics. New methods and analyses have been created in the last decade to obtain what could be considered their least studied property: their metallicity. The abundance of metals in their photospheres can provide key information to better understand the formation and evolution of planets, stars, and our Galaxy. In this talk, I will present the latest works and advances related to the metallicities of M dwarf stars, the challenges that the cool dwarf photospheres still present to us, and discuss what else is needed to obtain precise and consistent abundances for them, as it can be achieved for FGK stars.
FPGAs in space: current experiences, future challenges and opportunities
Speaker: Merodio Codinachs, David
Filiation: European Space Agency (ESA)
Date: October, 7th 2019
FPGAs are key components in space equipment due to their versatility and performance to implement digital functions. They are embarked in satellites and used in many applications; such as observing the earth, provide telecommunications and navigation services as well as to contribute to science and explore the wider Universe. The FPGAs face very different conditions in space compared to the terrestrial applications, especially due to the radiation environment, which limits the selection of the FPGAs that can be used. This talk will provide an overview of the current use of FPGAs in ESA missions and a short introduction to the radiation effects in the FPGAs, how they are analysed, tested and mitigated. The emerging private space industry or "new space", as well as, the nanosatellites have different requirements than the class 1 programmes. The points presented are becoming even more relevant and are including new challenges.
Searching extended line-emission objects in wide-field survey: The IPHAS experience
Speaker: Sabin, Laurence
Filiation: Instituto de Astronomia, UNAM, Ensenada, Mexico
Date: June, 17th - 28th 2019
Completeness is one of the major issues affecting the study of populations of Galactic and extragalactic sources. I have been working on the detection of extended emission-line nebulae of low surface brightness in the INT Photometric Halpha Survey of the Galactic Plane using a mosaicking technique. Various new symbiotic stars, supernova remnants and planetary nebulae that had escaped earlier screening have been discovered. I will present the characteristic of IPHAS and the detection methods that were used and how this experience can be used by other imaging and photometric surveys.
Back to Orion
Speaker: Rodrígues, Luis Felipe
Filiation: Universidad Nacional Autónoma de México (UNAM)
Date: June, 13th 2019
Orion is the massive star formation region closest to the Sun and in consequence it has been studied in detail. I will present three recent results from the IRyA group on in this region. The first one is the ultraprecise determination of the distance to Orion using VLBI observations of stars with either thermal or non-thermal emission. Finally, we will focus on the extraordinary “explosion” that seems to have taken place in the Orion BN/KL region. Not only the molecular gas but also several stars are receding from a point in common with velocities of hundreds of km/s for the gas and of tens of km/s for the stars. We will present the most recent data on the proper motion of the stars and discuss the models that have been proposed to explain this phenomenon.
CTA: the Cherenkov Telescope Observatory for VHE Gamma Ray Astronomy
Speaker: Martínez, Manel
Filiation: IFAE-BIST
Date: March, 28th 2019
The Cherenkov Telescope Array (CTA), currently in construction, shall be the Cherenkov Telescope Observatory for VHE Gamma Ray Astronomy, and shall provide crucial data for the understanding of the extreme universe in the recently open multimessenger era. The goals and characteristics of the project will be reviewed, and the current status and plans presented. In addition, the crucial role of the Spanish community in this project will be highlighted.