Colloquia

Flaring on the Sun at all scales
Speaker: Harra, Louise
Filiation: PMOD/WRC Davos, Switzerland
Date: April, 30th 2020
Abstract:
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 will be launched providing a third spectrometer probing the solar atmosphere. We will discuss future science goals in the coming years.
Star Formation in Nearby Galaxies: the promise of radio continuum
Speaker: Brinks, Elias
Filiation: University of Hertfordshire Centre for Astrophysics Research
Date: April, 2nd 2020
Abstract:
The Interstellar Medium (ISM) of star-forming galaxies is pervaded with cosmic ray electrons. They move at relativistic speeds and lose their energy in the form of synchrotron emission in the ever present magnetic field which is frozen in with the ISM. The recent, vast increase in sensitivity of radio interferometers now offers the prospect of using the radio continuum (RC) emission from normal star forming galaxies as a proxy for the spatially resolved star formation rate (SFR), virtually bypassing any of the extinction issues that plague optical/UV observations. Once properly calibrated, a non-thermal radio continuum - SFR relation will provide a robust, unbiased, extinction free tool for characterising the SFR in both the Local Universe and at high redshift in upcoming radio surveys with instruments such as the VLA, LOFAR, and SKA precursors. Moreover, detailed observations at multiple wavelengths across the radio part of the electromagnetic spectrum can be used to to improve our understanding of the physical origin of synchrotron emission and the various energy loss mechanisms involved. We have undertaken a sensitive, multi wavelength, high-resolution study using the VLA of a sample of 40 nearby dwarf galaxies (a proxy for early type galaxies) taken from the LITTLE THINGS survey. By combining our VLA observations with ancillary data including H-alpha, 24um, and the FUV we separate the radio continuum emission into its thermal and non-thermal components and compare these to the SFR. We use these results to calibrate the RC-SFR relation on scales from 200 to 700 pc, explore the equipartition magnetic field properties of the galaxies, and the intrinsic scatter in the RC-SFR relation.
Catalogue of dense molecular clouds in the Galaxy (ATLASGAL)
Speaker: Moore, Toby
Filiation: Astrophysics Research Institute, Liverpool John Moores University, Liverpool, UK
Date: March, 26th 2020
Abstract:
We have constructed the largest sample of dust-associated class II 6.7 GHz methanol masers yet obtained. New measurements from the the Methanol MultiBeam (MMB) Survey were combined with the 870μm APEX Telescope Large Area Survey of the Galaxy (AT- LASGAL) and the 850 μ m JCMT Plane Survey (JPS). Together with two previous studies we have now identified the host clumps for 958 methanol masers across the Galactic Plane, covering approximately 99 per cent of the MMB catalogue and increasing the known sample of dust-associated masers by over 30 per cent. We investigate correlations between the phys- ical properties of the clumps and masers using distances and luminosities drawn from the literature. Clumps hosting methanol masers are significantly more compact and have higher volume densities than the general population of clumps. We determine a minimum volume density threshold of n(H2)≥ 104 cm−3 for the efficient formation of intermediate- and high- mass stars. We find 6.7 GHz methanol masers are associated with a distinct part of the evolu- tionary process (Lbol/Mfwhm ratios of between 100.6 and 102.2) and have well defined turning on and termination points. We estimate the lower limit for the mass of embedded objects to be ≥ 6 M⊙ and the statistical lifetime of the methanol maser stage to be ∼ 3.3×104 yrs. This suggests that methanol masers are indeed reliable tracers of high mass star formation, and indicates that the evolutionary period traced by this marker is relatively rapid.
Young Runaway Stars
Speaker: Rodríguez, Luis Felipe
Filiation: Instituto de Radioastronomía y Astrofísica, UNAM, México
Date: February, 20th 2020
Abstract:
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
Abstract:
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
Abstract:
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
Abstract:
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
Abstract:
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
Abstract:
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
Abstract:
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
Abstract:
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
Abstract:
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
Abstract:
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
Abstract:
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
Abstract:
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
Abstract:
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
Abstract:
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.