Recent Talks

List of all the talks in the archive, sorted by date.

Tuesday April 11, 2023
Dr. Amirnezam Amiri
University of Florence and INAF-Arcetri - Italy



The abundance of chemical elements across cosmic time provide unique information on the physical processes driving the evolution of galaxies. Current methods for measuring gas-phase metallicities, based on either direct measurements of electron temperature (Te) or calibrations from strong nebular emission line ratios, are based on simplifying assumptions and do not adequately describe the complexity of the emitting regions. We present a new approach based on fitting galaxy spectra with multi-cloud photoionisation models. Unlike current methods, based on comparisons with single-cloud models, our methodology is able to reproduce all observed emission lines to a very high accuracy, down to a few percent, thus allowing for accurate metallicity measurements. We further recover the well known trends between ionization parameter and metallicity, and between the Nitrogen and Oxygen abundances. Our models accurately reproduce the auroral-to-nebular line ratios, while the results of the standard Tmethod are sometimes very different from the best-fitting model metallity. We finally present newly calibrated metallicity estimators for galaxies based on ratios between strong emission lines.

Friday March 31, 2023
Fernando Merlos García
Instituto de Astrofísica de Canarias / EST


El Telescopio Solar Europeo (EST), de clase cuatro metros, es un proyecto que se encuentra en su fase de diseño preliminar, previa a la fase de construcción. Con él se pretende aunar y mejorar las prestaciones de los actuales telescopios solares de clase un metro que están operativos. Uno de los principales objetivos en esta fase del proyecto es poder identificar, definir y gestionar los requisitos de cada una de sus disciplinas organizadas en los distintos paquetes de trabajo definidos. En esta charla se pretende mostrar las herramientas utilizadas para llevar a cabo esta importante tarea.


Thursday March 30, 2023
Dr. Noel Castro Segura
University of Southampton



Disc winds and jets are ubiquitous among accreting systems on all scales, from active galactic nuclei (AGN) down to young stellar objects. They represent a key mechanism through which these systems interact with their environment (“feedback") and may be responsible for triggering the mysterious state changes observed in X-ray binary stars (XRBs).

Transient low-mass X-ray binaries (LMXBs), harbouring a black hole or a neutron star, provide us with a natural laboratory for studying the connection(s) between accretion discs, jets and winds.  These systems undergo outbursts, during which they brighten dramatically across the whole electromagnetic spectrum. The outbursts typically last hundreds of days, recur on timescales of decades, and reflect a sudden increase in the accretion rate onto the compact object. Over the course of an outburst, LMXBs exhibit two distinct spectral states. These spectral states are thought to be a consequence of different accretion geometries close to the central object.

Remarkably, the two distinct accretion states also appear to produce two distinct types of outflows. Steady compact radio jets are only seen in the hard state, whereas evidence of disc winds originally came in the form of blue-shifted X-ray absorption lines associated with Fe ions detected only during the soft state. However, recent observations of disc winds in the far-UV, optical and NIR lines reveal a multiphase nature of these outflows that may be present across the entire outburst.  

I will discuss the current status of disc winds in LMXBs with special emphasis in the latest results from far-UV spectroscopy obtained with the Hubble Space Telescope.



Meeting ID: 868 2664 6040
Passcode: 610738



Tuesday March 28, 2023
Drs. Rita Tojeiro
University of St. Andrew


Galaxies and the dark matter halos in which they reside are intrinsically connected. That relationship holds information about key processes in galaxy and structure formation. In this talk, I will consider how the galaxy-halo connection depends on position within the cosmic web - the familiar decomposition of large-scale structure in filaments, knots and voids. Simulations demonstrate the various ways in which the cosmic web modulates the growth and dynamics of halos. The extent to which the cosmic web impacts on galaxies is more difficult to establish. For example, galaxies might be sensitive only to the evolution of the host halo, in which case any effect of the cosmic web on galaxies is secondary, and can be inferred from the halo's history. There is evidence, however - from simulations and observations - that the cosmic web also impacts on the evolution of galaxies via the effect it has on the broader gas ecosystem in which they are embedded, as well as through "pre-processing" effects on group scale. So, how should we think of the cosmic web in its role as a transformative agent of galaxies? And what physical processes can we convincingly constrain from observations and simulations? In this talk I highlight recent work that addresses these questions.

Friday March 24, 2023
Ángela Hernández Delgado
Instituto de Astrofísica de Canarias/ EST


El Telescopio Solar Europeo (EST), de clase cuatro metros, es un proyecto que se encuentra en su fase de diseño preliminar, previa a la fase de construcción. Con él se pretende aunar y mejorar las prestaciones de los actuales telescopios solares de clase un metro que están operativos. En esta charla se hará un repaso de las herramientas, diagramas, flujo de trabajo utilizado para la definición de los sistemas y subsistemas que abarca el ECS (EST Control System).

Unirse a la reunión Zoom:
ID de reunión: 857 6297 5287


Thursday March 23, 2023
Dr. Lorenzo Pizzuti
CEICO, Institute of Physics of the Czech Academy of Sciences


I present the recent results obtained using the updated version of MG-MAMPOSSt, a code that constrains modified gravity (MG) models viable at cosmological scales using determination of galaxy cluster mass profiles with kinematics and lensing analyses. I will discuss limitations and future developments of this method in view of upcoming imaging and spectroscopic surveys, as well as the possibilities of including X-ray data to break degeneracy among model parameters. Finally I will show preliminary results about the constraints that can be obtained on the inner slope of dark matter profiles when adding the velocity dispersion of the Brightest Central Galaxy (BCG) in the dataset of MG-MAMPOSSt.

Tuesday March 21, 2023
Dr. Scott Kenyon
CfA / Harvard & Smithsonian



Many (perhaps most) nearby white dwarfs have strong 
absorption lines from Ca, Si, Mg, Al, and other metals 
on optical and ultraviolet spectra. Abundance analyses 
suggest the ensemble of metals has a composition similar 
to asteroids or the cores of rocky planets. The atmospheric
diffusion times are much smaller than their ages. Thus, the 
metals must be continually replenished.  I will describe 
observations of these systems and outline an evolutionary 
path that allows material from an erstwhile planetary system
to end up on the surface of the white dwarf remnant of an
A-type main sequence star.

Tuesday March 21, 2023
Drs. Daniela Korkacova
Charles University (Czcech Rep.)


FS CMa stars are a subgroup of the B[e] stars. The forbidden emission lines and infrared excess are present in their spectra. This is a sign of very extended circumstellar region. While the B[e] phenomenon has been explained for other B[e] groups, the nature and evolutionary status of FS CMa stars has not been explained. Recently, we discovered very strong magnetic field in one of FS CMa stars, IRAS 17449+2320. The strength of the magnetic field modulus, about 6.2 kG, is in the order of the strongest Ap stars. The magnetic field together with other properties point to the post-merger origin of IRAS 17449+2320. It is very likely that other post-mergers are hidden among FS CMa stars.

The first results of our new N-body simulations show that more than half of mergers occurs in B-type stars. In other words, we are overlooking the most frequent channel of the mergers. This may have an important consequence for the enrichment of the ISM by heavier elements. Especially important it may be in the early universe.

Tuesday March 21, 2023
Dr. Angel de Vicente Garrido


In a time when we deal with extremely large images (be it from computer
simulations or from extremely powerful telescopes), visualizing them can
become a challenge. If we use a regular monitor, we have two options:

1) fit the image to our monitor resolution, which involves interpolation
and thus losing information and the ability to see small image details.

2) zooming in on small parts of the image to view them at full
resolution, which involves losing context and the global view of the
full image.

To alleviate these problems, display walls of hundreds of Megapixels can
be built, which allow us to visualize in full resolution small details
of the images while retaining in view a larger image context. For
example, one of the world's highest resolution tiled-displays is
Stallion (, at the TACC in
Texas, USA), with an impressive resolution of 597 Megapixels (an earlier
version of the system can be seen being used at

At the IAC we have built a more modest display wall (133 Megapixels),
which you probably have already seen in action in one of our recent
press releases ( In this talk I will
introduce this new visualization facility (which any IAC researcher can
use) and discuss on some design issues, possible current and future
uses, limitations, etc.

Friday March 17, 2023
Enol Matilla


Las estrellas en el cielo no están quietas. ¿Cómo podemos fotografiar el espacio sin que salgan movidas? Trípodes, monturas, sistemas de guiado y soluciones para conseguir estrellas como alfileres.

Unirse a la reunión Zoom
ID de reunión: 861 6896 0971