Found 20 talks width keyword spectroscopy

 The fate of massive stars and the type of supernova (SN) they produce are closely linked to their final stages of evolution. During these late phases, stars may undergo episodic mass loss, forming circumstellar material (CSM) that can leave observable signatures in the SN spectra, particularly as resonance lines in the near-ultraviolet (NUV). In this talk, I will present a sample of superluminous supernovae (SLSNe), an exceptionally luminous class of SNe, focusing on the NUV spectroscopy to search for signatures of recently ejected CSM shells. I will first discuss two SLSNe in which CSM shells are detected, inferring their properties and the timing of the ejection, along with implications for the underlying mass-loss mechanisms and progenitor systems. I will then extend the analysis to the full sample, modelling the spectral regions where CSM-related features are expected in order to evaluate how common such mass-loss episodes are and to place constraints on undetected CSM shells. These results provide new insights into the final stages of massive star evolution and help constrain the nature of SLSN progenitors.

Finally, I will summarise our ongoing JWST work within the GATOS (Galactic Activity, Torus and Outflow Survey) collaboration. In particular, I will focus on our recent study about the survival of PAH molecules in AGN-driven outflows.

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.

Automatización del POTEC

Explicación del problema de automatización del criostato de pruebas para la preóptica de Harmoni. Integración de diferentes protocolos de comunicación mediante el uso de lenguajes de alto nivel y un manejo de los errores que posibilite su integración dentro de un proceso industrial robusto acelerando el tiempo de prototipado y testeo. Uso de Python para la adquisición de datos y la supervisión del proceso en tiempo de ejecución.

Desarrollo de un sistema de medida optoelectrónico para la caracterización  de fotodetectores basado en un monocromador

Creación de una aplicación Python para el control de un sistema óptico y la toma de datos de dos picoamperímetros conectados a sendos fotodiodos que miden la intensidad de la radiación emitida. Esto nos servirá para la caracterización del fotodetectores

Tema: Seminario de Instrumentación: Presentaciones Becarios de Verano

Hora: 17 sept. 2021 12:00 p. m. Atlantic/Canary

Unirse a la reunión Zoom

https://rediris.zoom.us/j/81452070054

Youtube

https://youtu.be/7GSWv6mbQlg

The ExoMol project (www.exomol.com) provides comprehensive spectroscopic data (line lists) for the study of atmospheres of exoplanets and other hot bodies.  These line lists serve as input for models of radiative transport through hot atmospheres and are useful for a variety of terrestrial applications. The basic form of the database is extensive line lists; these are supplemented with partition functions, state lifetimes, cooling functions, Landé g-factors, temperature-dependent cross sections, opacities, k-coefficients and pressure broadening parameters. Currently containing 80 molecules and 190 isotopologues totaling over 700 billion transitions, the database covers infrared, visible and UV wavelengths. The field of the HR spectroscopy of exoplanets is growing extremely fast and urgently demands molecular data of high precision. Failure to detect molecules in atmospheres of exoplanets is often attributed to the lack of the underlying quality of
the line positions.  These developments have led us to begin a systematic attempt to improve the accuracy of the line positions for the line lists contained in the database. Our new ExoMolHD project aims to provide comprehensive line lists to facilitate their use in characterization of exoplanets using high resolution Doppler shift spectroscopy. Progress on this objective will be presented.

At present, our understanding of the formation history of the MW is limited due to the complexity of observing the imprints of accretion events and of reproducing them in numerical simulations. Moreover, though being the only galaxy, in which the Galactic potential can be probed in detail, the distribution of mass in the MW, and hence of the dark matter, is poorly constraint, especially at large distances. In addition, the MW is not isolated, and it has recently been suggested that the infall of the LMC can induce a perturbation in the stellar and dark matter distribution of the MW. As a consequence, the details of the formation history of our Galaxy are still unknown, such as the number of accretion events, the mass of the accreted galaxies, and the epoch of these events. Yet this information is crucial to understand our environment and to constrain the theoretical models and simulations that try to reproduce it.

One of the major challenges of the field is that a tremendous number of multi-aspect (astrometric, photometric and spectroscopic) observations at significant depth is required to study the morphology, the kinematics and the chemistry of the outskirts of our Galaxy, where are located the signatures of these events. Hopefully, the advent of recent and incoming complementary large surveys, such as the European Gaia mission, UNIONS (Ultraviolet Near Infrared Optical Northern Survey), Pristine, Pan-STARRS (PS), WEAVE or LSST (Legacy Survey of Space and Time), is offering a new global point of view on our Galaxy’s halo, allowing us to precisely probe the Galactic potential our the MW, and to retrace itsaccretion history.

In this talk I will present recent works that have been conducted to better catarerized our Galaxy and its history with some of the existing surveys mentioned above. In addition, I will present the major improvement that will bring this new generation of large, multi-aspect surveys, to study both our Galactic history, as well as the fundamental nature of the dark matter.

Durante este seminario se hará un recorrido sobre la instrumentación dentro del proyecto QUIJOTE, desde de los instrumentos ya existentes y su problemática hasta el estado actual de los instrumentos de nueva generación y los posibles desarrollos a futuro.

HORUS (High ResolUtion Spectrograph) es un espectrógrafo de alta resolución, instrumento visitante en GTC y disponible para la comunicad científica desde prinicipios de 2019. Instalado en la plataforma Nasmyth B, detrás de OSIRIS, comparte foco con él. En esta charla se describe su software de control, resaltando la implementación realizada para ser un instrumento visitante de GTC y cómo se ha resuelto el problema del apuntado de un objeto.

Atmospheric compositions can provide powerful diagnostics of formation and migration histories of planetary systems. In this talk, I will present the results of our latest survey of atmospheric compositions focused on atmospheric abundances of H2O, Na, and K. We employ a sample of 19 exoplanets spanning from cool mini-Neptunes to hot Jupiters, with equilibrium temperatures between ~300 and 2700 K. We employ the latest transmission spectra, new H2 broadened opacities of Na and K, and homogeneous Bayesian retrievals. We confirm detections of H2O in 14 planets and detections of Na and K in 6 planets each. Among our sample, we find a mass-metallicity trend of increasing H2O abundances with decreasing mass, spanning generally substellar values for gas giants and stellar/superstellar for Neptunes and mini-Neptunes. However, the overall trend in H2O abundances, is significantly lower than the mass-metallicity relation for carbon in the solar system giant planets and similar predictions for exoplanets. On the other hand, the Na and K abundances for the gas giants are stellar or superstellar, consistent with each other, and generally consistent with the solar system metallicity trend. The H2O abundances in hot gas giants are likely due to low oxygen abundances relative to other elements rather than low overall metallicities, and provide new constraints on their formation mechanisms. Our results show that the differing trends in the abundances of species argue against the use of chemical equilibrium models with metallicity as one free parameter in atmospheric retrievals, as different elements can be differently enhanced.

Zoom link: https://rediris.zoom.us/j/92734027825