Últimas charlas

Todas las charlas en el archivo, ordenadas por fecha.


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Friday November 26, 2021
Carlos Martín Díaz
IAC

Abstract

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.


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Thursday November 25, 2021
Prof. Elisa Díaz González
ULL

Abstract

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. 

 


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Thursday November 25, 2021
Dr. Florent Renaud
Lund Observatory

Abstract

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.


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Tuesday November 23, 2021
Dr. Dainis Dravins
Lund Observatory (Sweden)

Abstract

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.


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Tuesday November 23, 2021
Dr. Eva Villaver
CAB

Abstract

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.

 



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Friday November 19, 2021
David Hernandez Expósito
IAC

Abstract

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).

El IAC, a través del consorcio español S3CP (Spanish Space Solar Physics Consortium), contribuye a la instrumentación de SUNRISE III mediante el diseño electrónico del frame grabber y las cámaras para los instrumentos TuMag y SCIP. En esta charla se describirá el estado actual del frame grabber. Este dispositivo, basado en FPGA y diseñado ad-hoc para la ocasión, es responsable de las tareas de adquisición y procesado de imágenes en sincronismo con los elementos ópticos, generación de cabeceras, toma de housekeeping así como la configuración y control de las cámaras.

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Tuesday November 16, 2021
Dr. Andrea Negri, Dr. Carlos Allende
IAC

Abstract

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.


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Thursday November 4, 2021
Dr. Sergio Contreras
DIPC

Abstract

 

On the LCDM cosmology, dark matter collapses into virialised objects called haloes. The abundance and distribution of these haloes are a direct consequence of the cosmology of the Universe. By constraining the dark matter halo clustering, we could also constraint the cosmology from our Universe. Since dark matter haloes can not be observed, we need to use galaxies to trace them.

In this talk, I will present a new method that we develop capable of constraining cosmological information from the redshift space galaxy clustering.  We use the scaling of cosmological simulations and the SubHalo Abundance Matching extended (SHAMe) empirical model to produce realistic galaxy clustering measurements over a wide range of cosmologies. We generate more than 500,000 clustering measurements at different cosmological and SHAMe parameters to build an emulator capable of reproducing the projected correlation function, monopole and quadrupole of the galaxies. We run an MCMC using this emulator to constrain the cosmology of the TNG300 hydrodynamic simulation. We correctly predicted the cosmology of the TNG300 simulation constraining sigma8 between [0.75,0.83] and Omega matter h^2 between [0.127,0.162]. The best constraints are obtained when including scales below 2 Mpc/h and when combining all different clustering statistics. We conclude that our approach can be used to constrain cosmological and galaxy formation parameters from the galaxy clustering of galaxy surveys.

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Thursday October 28, 2021
Dr. Slava Lukin
NSF

Abstract

The phenomenon of magnetic reconnection in a magnetized plasma has been a subject of numerous studies over the past several decades in a variety of contexts, from high energy astrophysics, to solar and space physics, to laboratory-based experiments.  However, most magnetic reconnection studies have been devoted to exploring different collisionality regimes in a fully ionized single specie plasma.  Until recently, the physics of magnetic reconnection in partially, and weakly, ionized plasmas has received relatively little attention.  In this talk, I will provide a brief overview of the physical effects that partial ionization of the ambient medium may introduce in the dynamics of magnetic reconnection, with a particular focus on the environment of the lower solar atmosphere.


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Tuesday October 26, 2021
Dr. Faith Vilas
PSI

Abstract

During the past 50 years, we have witnessed humankind’s first good, detailed look at the planets in our known Solar System.  All of these advances built upon Earth-based telescopic observations.  We predict surface conditions on other Solar System bodies before spacecraft reach them for in situ study.  The dominant type of asteroid identified telescopically in the main asteroid belt is classed as a C-complex asteroid, likely the origin of many of the primitive carbonaceous chondrite meteorites.

In the visible spectral region, one prominent, identifying spectral feature indicating the presence of Fe2+ → Fe3+ in clay minerals is located near 0.7 µm in over half of the C-complex asteroids.  Using its spectral presence, we can constrain the presence and thermal history of these objects in the Solar System.  I will describe the feature, and the implications of the evidence of its presence.  As an illustration, I will then show how we can use the presence of this feature to probe Solar System developmental history through examining the spectra of the jovian outer irregular satellites.

 



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