Recent Talks

On the Sun, the presence of magnetic flux at the photosphere is closely linked to (1) steady heating of the overlying atmosphere and (2) transient brightenings, the largest of which are flares.   I will discuss statistical properties of both phenomena, with an emphasis on aspects of each that might apply to other astrophysical objects, such as other stars or stellar remnants, and perhaps AGNs.  Regarding heating, power-law scalings have been found to relate magnetic flux with steady coronal emission in both soft X-ray (SXR) and EUV ranges.  A key observation is that the details of magnetic structure (field strengths and their spatial gradients, including measured electric currents) appear not to affect heating rates. Similar SXR scalings have been reported for G,K, and M dwarfs and classical T-Tauri stars.  Departures from such scalings, whether on the Sun, other stars, or other objects, might reveal important aspects of the heating mechanisms that drive steady emission, and should be sought.   Regarding flaring, again a power-law scaling between magnetic flux and flare SXR emission has been found, but with a different exponent.  Differences in these scalings suggest that steady heating fundamentally differs from flare heating, disfavoring the “nanoflare” hypothesis (i.e., that steady coronal heating arises from many weak, unresolved flares that are essentially scaled-down versions of larger flares).  Analogous differences in the scalings of steady vs. flaring luminosities with magnetic flux on other objects could constrain processes driving each type of emission.  Another key property of flares is that they extract energy from the magnetic field, which in the solar case leads to measurable changes in field strengths after flares – photospheric field strengths tend to increase, coronal fields tend to decrease.  It is possible that analogous changes could be observed on other stars or objects (via, e.g., Zeeman or synchrotron  methods). 

Se cuenta la historia de la integración del subsistema Fiber Link (FL) en el telescopio de 3.6 m del Observatorio de La Silla para alimentar el espectrógrafo NIRPS. NIRPS es un espectrógrafo de alta resolución y ultraestabilidad optimizado para el rango infrarrojo cercano del espectro. Compartirá foco con el instrumento HARPS y su finalidad principal es el estudio de exoplanetas. El subsistema FL permitirá alimentar al espectrógrafo con la luz procedente del telescopio y optimizará la estabilidad de todo el sistema.

Over the past decade, our understanding of the Large Magellanic Cloud (LMC) and its relationship to the Milky Way (MW) has undergone a paradigm shift. The LMC now appears to be on the order of 20% of the MW mass. At this mass, the LMC creates large dynamical effects, opening up new avenues for studying the MW in cosmic context, time-dependent dynamics in general, and even the nature of dark matter. I will discuss (1) how the LMC is strongly deforming the MW by displacing the MW stellar disc, (2) how the MW-LMC pair fits in our understanding of hierarchical galaxy assembly, and (3) what the LMC can tell us about terrestrial searches for dark matter. I will also present the theoretical tools driving the science, including methods for flexibly parameterising time-dependent dynamics, as well as robust methods for studying the stability of dynamical systems.

Zoom: 

https://rediris.zoom.us/j/81076006712?pwd=VWNHSS94dFBPS3YyNlpsellIdG1hUT09

Meeting ID: 810 7600 6712            Passcode: 304299

Youtube: https://youtu.be/Puv8s0j7HwY

I will discuss the location of rather extreme galaxy populations in two of the most important scaling laws for disc galaxies: the baryonic Tully-Fisher relation (BTFR) and the specific angular momentum-mass relation. First, I will present recent results on the dynamics of gas-rich, extended low surface brightness galaxies, sometimes called ultra-diffuse galaxies (UDGs). Using a robust kinematic modelling fitting technique, we find that gas-rich UDGs are outliers of the BTFR and have baryon fractions as high as the cosmological average. Moreover, I will show that mass models of a gas-rich UDG cannot be reconciled with a standard cold dark matter halo. In the second part of the talk, I will present new measurements of the stellar, gas, and baryonic specific angular momenta of disc galaxies, to then derive the relations between the specific angular momenta (j) and mass (M). I will report the discovery of empirical correlations between j, M, and the gas fraction. These relations are very tight and are followed very well not only by normal galaxies but also by a set of extreme galaxies that are outliers of other scaling relations. Our scaling laws provide a direct benchmark to test the outcome and predictions of hydrodynamical simulations and semianalytical models.

El IAC es uno de los socios principales en el proyecto NRT (New Robotic Telescope)  para el diseño y construcción de un telescopio de 4 m robótico que estará ubicado en La Palma. El telescopio será un referente mundial en la caracterización de fenómenos astronómicos de naturaleza transitoria (supernovas, estallidos de rayos gamma, contrapartidas de lentes gravitatorias, etc). El funcionamiento enteramente robótico y la rapidez de respuesta (<30 s) presenta numerosos retos en diversas áreas tales como mecánica, optomecánica y sistema de control. El espejo primario de NRT será de carácter segmentado y formado por 18 hexágonos de 1 m en una configuración de tres anillos concéntricos.  El proyecto ha sido el motivador para el desarrollo de  CSOA (Centro de Sistemas Ópticos Avanzados) en el que se fabricarán los espejos del primario y del secundario de NRT y que representa un cambio de primer orden en las capacidades para el desarrollo de óptica de telescopios e instrumentación astronómica en España.  En esta charla se presentará el estado del proyecto y las previsiones hasta la puesta en funcionamiento del telescopio con especial atención a las actividades lideradas por el  IAC

In this talk I will review my recent work using the MaNGA dataset. MaNGA is an IFU survey which provides high spatial and spectral resolution of ~10,000 galaxies for its final data release (DR17). The IFU observations allow to derive spatially resolved stellar populations for galaxies up to ~1.5Re. I will show results on the stellar population gradients (age, metallicity, alpha-elements) of early-type galaxies (ETGs) divided into lenticular (S0), fast-rotating and slow rotating ellipticals (FR-E, SR-E) and their implications for the formation of massive galaxies. I will also show results from the PCA analysis of the MaNGA spectra of the S0 population, pointing towards the existence of two distinct populations following different evolutionary tracks. I will  discuss the impact of initial mass function gradients on the estimations of stellar mass and their effect on the values of mass/light effective radii. MaNGA observations have also been critical to identify a sample of ~20 hidden AGNs missed by integrated spectroscopic surveys (SDSS). Finally, I will show preliminary results on the identification of a relic galaxy candidate.

Zoom Link: 

https://rediris.zoom.us/j/83003821615?pwd=M0FGY2NjdEphb0hEbEhRTVJLcnh2QT09
Meeting ID: 830 0382 1615
Passcode: 439318

YouTube: https://youtu.be/yIDvf5-_AsI

Accurate non-LTE modelling of stellar spectra, and thus the derivation of accurate stellar properties such as chemical composition, temperature, and surface gravity, depends on reliable atomic data.  While inelastic electron collisions are very important even in FGK stars, the relative importance of the more abundant yet less efficient hydrogen collisions has for a long time been a major source of uncertainty.  Over the last decades, considerable progress has been made on the theoretical side, as well as with experiments for the important charge transfer processes involving hydrogen, both covering a significant number of astrophysically important atoms.  I will review this progress, and discuss where further progress might be needed.

Eclipse Foundation AISBL[1] is the biggest Open Source organization within the EU. It the home for over 400 projects[2] covering a wide range of knowledge areas. It also hosts 18 groups of companies (Working Groups) forming an ecosystem of over 300 organizations[3] that supports the development of many of these projects, as well as the creation of a variety of specifications within different industries.

Eclipse Foundation has a long history of fruitful relations with research and development projects[4] and organizations worldwide, and specifically in Europe.

During this session, an introduction of Eclipse Foundation will be delivered, insisting on our main value proposition, followed by a short description of some of the most relevant projects, especially in the area of Research, in which we are involved.

We will finalise the presentation describing how The Eclipse Foundation interacts with these R&D organizations and institutions as a needed requirement towards exploring together potential collaboration vectors in the near future.

En este seminario se dará una pequeña introducción al desarrollo de interfaces gráficas para GTC