List of all the talks in the archive, sorted by date.
One prediction of ΛCDM is the existence of partially phase-mixed substructures from accreted dwarf galaxies in the Milky Way stellar halo. Substructure originating in a single accretion event can be readily identified as a tight cluster of stars in phase space with similar chemical properties. Recently, the discovery of the Gaia Sausage Enceladus (GSE) has revolutionised our understanding of the complex assembly of the Milky Way halo. We present a review of the chemistry that characterises the last major merger that happened to the Milky Way some 9-10 Gy ago.
Galactic globular clusters have always been at the crossroad of several investigations in both Stellar and Galactic Astrophysics. For long time, they have been considered the prototypes of Simple Stellar Populations, and hence used for testing and calibrating stellar evolutionary models as well as population synthesis tools. Nowadays, after the discovery of the presence of multiple stellar populations in almost all Galactic GCs, we know that this assumption is no longer valid. The process(es) of formation and early evolution of these star clusters is (are) very far to be understood, and any scenario so far envisaged is severely challenged by the pletora of empirical evidence collected till now. In the same time, thanks to the availability of an impressive observational framework - collected by combining kinematic measurements from Gaia mission, with data provided by large spectroscopic and photometric surveys -, GCs are playing a crucial role for our understanding of the assembly history of the Milky Way. We will review our present knowledge about these important stellar systems, discussing the several, open issues related to their formation/evolution, and discuss how we can use them in our effort to depict the Milky Way assembly history.
Containers are portable environments that package up code and all its dependencies so that an application can run quickly and reliably from one computing environment to another. Most people are probably familiar with full virtualization environments (such as VirtualBox), so in this talk we will explain the main differences between full virtualization and containers (sometimes called light-weight virtualization), and when to use each.
At the same time, not all container technologies have the same goals and/or approaches. Docker is the most mature container offering, but it is geared mainly towards micro-services. Singularity is a newer contender, with an emphasis on mobility of compute for scientific computing. We will introduce both softwares, showing how to create and use containers with each of them, while discussing real-life examples of their use.
The lecture notes can be found here:
In the local universe most of the stellar mass is in passive galaxies, where star formation is
absent or at very low levels. Understanding what are the mechanisms that have been
responsible for quenching star formation in galaxies, and transforming them into passive,
quiescent systems, is one of the main observational and theoretical challenges of extragalactic
astrophysics. I will give a brief overview of the several possible quenching causes and physical
processes that have been proposed so far, ranging from feedback from black hole accretion and
starburst activity, to effects associated with the large scale environment in which galaxies live.
Although most of these mechanisms and causes play a role in different classes of galaxies and
at different epochs, multi-band observations are providing growing evidences that just a few of
them play the key, dominant role.
I will conclude by providing prospects for further investigating these aspects and tackling open
questions with the next generation of observing facilities.
Mark I is a part of the origin of the IAC, operating in the El Teide Observatory since 1975, in three different locations until reaching the Solar Pyramid "van der Raay" in 1987. Every day, weather permitting, it has been providing precise measurements of the radial velocity of our star. It began to perform continuous daily observations from July 1984 and, until December 2020, 10169 out of 13408 possible days (76%) useful data has been gathered. Designed, updated, maintained and operated by the Helioseismology team at the IAC and the University of Birmingham (UK), more than 100 people, from TOTs and weekend fellows to professors, have contributed to this endeavour. It was a true pioneer, key in the birth and development of Helioseismology and Astroseismology as branches of modern Astronomy.
Mark I is a resonant scattering spectrophotometer that measures the radial velocity of integral sunlight using the KI-769.9 nm spectral line. It has been a pioneer and reference for calibration of other instruments: MarkII, IRIS, Cannon, Stellar, Space, BiSON, GOLF, which have also worked in different ground-based observatories and in space missions such as SoHO (1995-).
Its precision, in a single measurement of the solar radial velocity, is less than 1 m/s, and the one achieved so far is less than 1 cm/s at frequencies around 0.1 mHz (gravity modes zone) and less than 1 mm/s at 3 mHz (acoustic modes zone). It measured for the first time the spectrum of solar acoustic modes (from 1.8 to 4.2 mHz) of small degree (ℓ <= 3): their frequencies, amplitudes and lifetimes, their rotational splitting; also its variations with the cycle of solar activity. He has explored gravity modes, measured the spectrum's background, and determined the acoustic cut-off frequency in the solar photosphere. All this has led to numerous discoveries that have been published in around 40 doctoral theses at different universities and more than 600 papers in international journals and books. These works have been already cited around 10,000 times in scientific literature.
In this talk I will briefly review its history throughout more than 45 years, an entire academic life, and I will raise some suggestions on its scientific use from now on.
Saliéndome un poco de la tónica habitual de los seminarios de Instrumentación, donde los ponentes muestran un aspecto determinado del trabajo que están realizando en su proyecto, yo he preferido retomar una presentación que hice en 2015 con motivo del Día de Nuestra Instrumentación y actualizarla y ampliarla. Bajo el título de "Catástrofes y accidentes astronómicos", en esta presentación mostraré lo peligroso que pueden ser los incendios, huracanes y terremotos en los telescopios, junto con los efectos de algunos accidentes y fallos humanos. He centrado la presentación en los casos más llamativos y, sobre todo, en aquellos donde he encontrado disponible material gráfico.
La realización del Proyecto de identificación, clasificación, valoración y propuestas de medidas para la conservación de litografías y otras obras del Instituto de Astrofísica de Canarias (A20100211/20100165-FGULL) ha mostrado las diversas tipologías que conforman el patrimonio de dicha institución. Durante esta charla daremos a conocer este patrimonio centrándonos en la obra seriada de artistas nacionales e internacionales de reconocido prestigio, que utilizan técnicas de grabado calcográfico y técnicas de estampación planas en su universo gráfico.
The formation and evolution of galaxies across cosmic time proceeds in different phases, paced by their internal evolution and external factors like gas accretion and mergers. The complex and always changing interplay between these mechanisms drives the assembly of galaxies and the physical conditions for star formation, which leaves observable imprints on the stellar populations. Large astrometric and spectroscopic surveys (e.g. Gaia, APOGEE, GALAH) collect the signatures of these past events in the building history of the Milky Way. However, simulations and models are necessary to decode the data. In this talk, I will present results from a series of hydrodynamical simulations of Milky Way-like galaxies, both in isolation and in cosmological context using the VINTERGATAN simulation. I will show the crucial role of mergers, and of the end of the merger phase, in forming the thick and thin Galactic discs, and making the transition between the two. I will then nuance this conclusion by explaining why the secular consumption of gas enables a similar transition, as well as the emergence of spirals, without any external factors.
The new generation of spectrometers designed for extreme precision radial velocities enable correspondingly precise stellar spectroscopy. It is now fruitful to theoretically explore what the information content would be if stellar spectra could be studied with spectral resolutions of a million or more, and to deduce what signatures remain at lower resolutions. Hydrodynamic models of stellar photospheres predict how line profiles shapes, asymmetries, and convective wavelength shifts vary from disk center to limb. Corresponding high-resolution spectroscopy across spatially resolved stellar disks is now practical using differential observations during exoplanet transits, thus enabling the testing of such models. A most demanding task is to understand and to model spectral microvariability toward the radial-velocity detection of also low-mass planets in Earth-like orbits around solar-type stars. Observations of the Sun-as-a-star with extreme precision spectrometers now permit searches for spectral-line modulations on the level of a part in a thousand or less, feasible to test against hydrodynamic models of various solar features.
- Seminario de Instrumentación. Progress on IFU development for solar observationsSilvia Regalado OlivaresFriday January 21, 2022 - 12:00 GMT (Aula)
- IAU G5 -- The GALAH survey: science goals and highlights to dateSarah MartellTuesday January 25, 2022 - 10:30 GMT (Online)