Recent Talks

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.

Planetary systems have been found systematically orbiting main sequence stars and red giants. But the detection of planets per se during the white dwarf phase has been more elusive with only 3 systems.  We have, however, ample indirect evidence  of the existence of planetary debris around these systems in the form of material acreted onto the white dwarf, disks and even planetesimals. In this talk, I will review how we can put the pieces together: how we can reconcile what we see in white dwarfs with what we can infer regarding the evolution of planetary systems from the main sequence phase.

Sunrise III es un observatorio solar diseñado para realizar observaciones epesctropolarimétricas a bordo de un globo estratosférico. Este observatorio cuenta con un telescopio de un metro de apertura que da luz a tres instrumentos posfocales principales: SUSI (Sunrise Ultraviolet Spectropolarimeter and Imager), SCIP (Sunrise Chromospheric Infrared spectra-Polarimeter) y TuMag (Tunable Magnetograph).

What is academic freedom? Why do we need it? What specific rights do we have as teachers and researchers? These questions are addressed in relation to the UNESCO 1997 recommendation for higher-education teaching personnel. It is observed that having good rules and regulations is one thing, what happens in practice often quite another. The final part of the talk lists the main current threats to academic freedom in the Western world and what can be done to counter them by efficient means, with a case study from Sweden.

____________________________

[English version below]

Extracto del Acta del Comité Director del IAC del 24 de noviembre de 2021:

“En relación con el seminario impartido recientemente en el IAC por el Prof. Erik J. Olsson (Univ. de Lund), la Dirección del centro lamenta profundamente que en el transcurso del mismo se realizaran afirmaciones absolutamente contrarias con nuestro firme compromiso con la igualdad de género y con los principios de nuestro Código Ético.

 Este profesor no se encontraba en visita de trabajo en nuestro centro. Su ponencia fue propuesta, de manera puntual, por un investigador del IAC a la Comisión de Seminarios, quien revisó el título y el resumen facilitados de la ponencia. Esta Comisión, por la información proporcionada, no podía deducir los contenidos totalmente inapropiados que finalmente fueron expuestos en varias transparencias y manifestados verbalmente por el referido ponente.

 La Dirección del centro expresa su rotunda desaprobación ante lo ocurrido y mantiene la medida de cancelar la distribución y el acceso a la ponencia a través de los medios de comunicación propios del centro; confirmando  la acción tomada, como medida preventiva por el Director, en el momento en el que se tuvo noticia de lo ocurrido.

 Se recuerda la responsabilidad que tiene todo el personal del centro con el cumplimiento de nuestro Código Ético, y los principios y fines del IAC en el desarrollo de nuestra actividad. Este compromiso es extensivo al personal externo que sea invitado para la realización de actividades en nuestro instituto.”

______

[Text extracted from the acts of the Direction Committee meeting held on November 24th 2021]

"In relation with the seminar recently given by Prof. Erik J. Olsson (Univ. of Lund, Sweden), the IAC Direction deeply regrets statements made during that seminar since those statements fully oppose our firm committment towards gender equality and the principles of our ethical code.   

Prof. Olsson was not in an offical visit at IAC. His seminar had been proposed to the IAC's Seminar Commission by an individual senior researcher at IAC. This Commission revised the title and the abstract provided for this talk, from which it could not foresee the totally inappropriate content exposed in several slides, and verbally manifested by the speaker.

The direction of IAC expresses its absolute dissaproval of these events, and maintains its measure of blocking all institutional channels for the access and/or distribution of the recording of this seminar. Hereby we confirm that measure, which was adopted preliminarily by the IAC's direction when it was first informed of these events.

We remind all IAC staff of our responsibility towards the observation of our Ethical Code, together with the IAC's principles and objectives in the development of all our activities. This committment is extended to any external personnel that is present at our institution.”

______

We will introduce several ways in which trivially embarrassingly parallel tasks can be run in laptops and desktops. We will introduce command-line tools such as GNU parallel and Kiko. We will then focus on simple techniques for optimisation of scientific computations in python. We will cover parallel computing with multiprocessing, acceleration of functions via numba, and GPU computing with cupy. The goal is to provide an easy roadmap for python code optimisation methods that can applied on already existing code, without writing a single line of C or FORTRAN.

In the aftermath of the cataclysmic explosion of massive stars, a vast zoology of source type is observed such as Supernova Remnants (SNRs), pulsar wind nebulae, pulsars and ‘zombie’ pulsars. Due to high velocity shock-waves combined with a high magnetic field or fast rotation in the case of pulsars, an efficient particle acceleration is achieved in those objects which are believed to be significant contributors to the pool of Galactic cosmic rays.
This seminar will start with a short introduction on particle acceleration and SNR physics, present the current scientific questions, and what we’ve learned from high-energy observations in the recent years.

On a more technical note, I will also present a new analysis method to fully exploit the multi-dimensional (X, Y, Energy) nature of X-ray data. This blind source separation method draws from the most advanced signal processing techniques to capture and disentangle the wealth of information contained in deep archival observations.

Zoom: 
https://rediris.zoom.us/j/86212537380?pwd=MGdYSE1rVDAyVlVESFE5RWEwOVlqZz09
Meeting ID: 862 1253 7380Passcode: 431670

YouTube: https://youtu.be/YwuCrGmp9_w