List of all the talks in the archive, sorted by date.
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.
Increasing light pollution is a threat to the research capacity of astronomical observatories. The case of the Teide observatory is not an exception, despite the OPTC's sustained protection efforts. We now have powerful modeling tools to theoretically test the impact of a change of lighting devices on the quality of the starry sky. During this project, we will use the Illumina numerical model to create the first decision-making tool aimed at maximizing the restoration of research capacity of an observatory. This innovative tool will actually be used for the restoration of the night sky at the Teide observatory. It will take the form of an excel page, that make it possible to independently modify the conversion plans for each municipality of the island of Tenerife and to determine the related reduction of the sky brightness. It will therefore be possible to target the most effective actions to restore the quality of the night sky at the observatory. The tool will use many pre-executions of the Illumina model. In situ measurements will be also carried out to characterize the current lighting infrastructure, a crutial input to the model.
Traditional Searches for Extraterrestrial Intelligence (SETI) use large radio telescopes to look for artificial signals from specific stars. In the era of large astronomical surveys, it is now possible to efficiently search for objects having certain predicted signatures of astro-engineering. In this talk, I present an international, cross-disciplinary project between astronomers and researchers in machine learning, the "Vanishing and Appearing Sources during a Century of Observations" (VASCO) project, where we scan the sky for objects that have physically disappeared from (or appeared on) the sky during the last decades. Some of the contaminants we expect are variable astrophysical objects with decade-long time scales. We compare the USNO to PanStarrs catalogues using several epochs of observations. Here, I present the updates about the candidate from the pilot paper (Villarroel+ 2016) and the discovery of ~100 transients (~1/3rd with amplitudes larger than 5 mags). The final goal of the project is to identify interesting astrophysical targets for follow-up analysis with extreme, exotic or bizarre patterns of variability.
We review some ideas and facts and disputes related to the research about the stellar density distribution in the Galactic bulge in the last decades: the discovery of the bulge triaxiality, boxiness, the long-bar as an extra component or as an extension of the own bulge (1st dispute), or the proposal of its X-shape form that has been criticized as an artifact due to an inappropriate use of red clumps as standard candles (2nd dispute).
Most of what we know about the masses and radii of stars comes from the studies of eclipsing binary stars (EBs). As the physical principles that govern the motion are well understood, modelling EB data represents a tractable geometrical problem. The attained accuracy of fundamental parameters is ~2-3% in the best possible cases (Torres et al. 2010), which plays a paramount role in stellar astrophysics: these results are used to calibrate the mass-radius relationship, critically test stellar evolution models, provide fundamental parameters (temperature, luminosity, mass and radius) for stellar and substellar objects across the main sequence, and anchor the distance scale. Given that so much in stellar astrophysics hinges critically on the values derived from EBs, we naturally wonder whether there are any circumstances that would allow us to beat down the uncertainties by another order of magnitude, say to a ~0.2-0.3% level, and thus achieve a 10-fold increase in calibration and gauge reliability. This could be done if the correlations between parameters were somehow reduced, and solution degeneracy somehow broken. If, for example, we had a third star in the system that happens to eclipse the binary, then the shapes of extraneous eclipses in a light curve would constrain the orbital inclination and stellar radii much more than the binary eclipses alone.
In this talk, I will discuss these and similar considerations and show what Kepler, K2 and TESS missions brought to the table.
The Observatorio de Canarias (OOCC) provide a unique and fundamental resource
for the IAC community. A large number of different facilities, from small telescope
to the GranTeCan, are available through a variety of channels and with different
possible observing modes.
This talk introduces the ongoing effort of a working group created to
1) evaluate the current use of the OOCC facilities
2) gather ideas for improving the effectivity of the observing process (preparation, observations, data processing) and for suggesting the implementation
of possible future instrumentation.
Breakthrough Starshot is an initiative by the Breakthrough Foundation to prove ultra-fast ultra-light nanospacecraft can be launched by laser radiation pressure to nearby stars, and will lay the foundations for a first launch to Alpha Centauri within the next generation. Designs for a 0.2c Alpha Centauri mission minimize beam director capital cost by accelerating a ~4 m, several gram diameter sailcraft for ~10 min. A number of hard engineering challenges remain to be solved before these missions can become a reality: Large coherent laser arrays are required. No consensus has been reached on the most suitable sail geometry for stable flight, “beam-riding”. The sail itself requires major advances in materials science and photonic design to produce materials with the required absorptance, emittance, reflectance, areal density and operating temperature. Along the way, the project will enable increasingly fast outer solar system and interstellar precursor missions. Breakthrough Starshot will pave the way for multi-lightyear pipelines of sailcraft that fly past each target star every few weeks. Beams such as Starshot will produce an extremely observable transient feature of Earth and therefore could be an observable of extraterrestrial advanced civilizations.
El coste de los mayores telescopios actualmente en construcción es tal que la extrapolación de estos diseños a tamaños superiores a ~50 metros de diámetro parece inviable. Futuros telescopios gigantes deberán de construirse siguiendo modelos nuevos, algunos ya propuestos, otros aún en fase de desarrollo.
We are developing and will commission a space debris and satellite imaging system in New Zealand to improve image resolution of Earth orbiting objects. Our simplified, low-cost approach is based on restricting possible regions where orbiting satellites and large space debris objects pass through the Galactic plane, where they can be detected within a background of natural stars. We will use a modular, wide-field adaptive optics (AO) system to estimate the spatially variant point spread function (SVPSF) using multiple natural guide stars (NGSs) to compensate for atmospheric turbulence over a wide field-of-view (FoV). To achieve this, our custom designed geometric wavefront sensor will provide estimates of phase perturbations from three or more isoplanatic patches. A combination of closed- and open-loop adaptive optics is employed. The closed-loop system will use a bright NGS for low-order aberration reduction using a Shack Hartmann wavefront sensor for correcting the optical path using a tip/tilt mirror system in real-time. Our open-loop system will estimate wavefronts from three of more natural stars and use atmospheric tomography to determine the SVPSF, off-line. From the SVPSF estimate, deconvolution from wavefront sensing is used to remove high-order aberrations fast moving target objects that will be imaged using a separate detector, synchronised with our AO cameras. A model for this hybrid AO system is described in this talk and its implementation will provide a platform to test novel methods for system refinement.
- IAU G5 -- The GALAH survey: science goals and highlights to dateSarah MartellTuesday January 25, 2022 - 10:30 GMT (Online)
- Dynamos, the drivers of solar and stellar activityProf. Axel BrandenburgThursday January 27, 2022 - 10:30 GMT (Online)