List of all the talks in the archive, sorted by date.
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.
I will provide highlights of work at the Space Telescope Science Institute (STScI), which provides science and operations support for NASA's space missions, delivers added value to data archives, and engages the public in the corresponding scientific results. We are preparing for continuing operations of the Hubble Space Telescope through 2025, looking forward to the launch of the James Webb Space Telescope, and contributing to the development of the Wide Field Infrared Survey Telescope. Staff at STScI are also advancing technology and scientific concepts for future flagship space missions.
Emerging flux regions (EFRs) are seen as magnetic concentrations in the photosphere of the Sun. From a theoretical point of view, the EFRs are formed in the convection zone and then emerge because of magnetic buoyancy (Parker instability) to the solar surface. During the formation process of EFRs, merging and cancellation of different polarities occur, leading to various configurations of the magnetic field. Often, EFRs are visible in the chromosphere in form of magnetic loops loaded with plasma, which are often called “cool loops” when seen in the chromosphere along with dark fibrils and they can reach up to the corona. Nowadays, we refer to them as an arch filament system (AFS) which connects two different polarities. The AFSs are commonly observed in several chromospheric spectral lines. A suitable spectral line to investigate chromospheric features and particularly AFSs is the He I 10830 Å triplet. The new generation of solar telescopes and instruments such EST and DKIST, will allow us to record very high spectral, spatial, and temporal resolution observations necessary to investigate the dynamics, magnetic field, and characteristics of AFSs. These observations will help us to answer many open questions related to flux emergence such: (1) What are the observational consequences of the emerging flux? (2) How do EFRs evolve with time in the different layers of the solar atmosphere and how are these layers linked? (3) Is it possible to measure the height difference between the photosphere and the chromosphere connected by the legs of the AFSs?
- TBDDr. Mahmoudreza OshaghTuesday November 10, 2020 - 12:30 (Online)
- Galacto-archeology (TBC)Dr. Andrea MiglioTuesday November 17, 2020 - 12:30 (Aula)