Recent Talks

Planets orbiting close to hot stars experience intense extreme-ultraviolet radiation, potentially leading to atmosphere evaporation and to thermal dissociation of molecules. However, this extreme regime remains mainly unexplored due to observational challenges. Only a single known ultra-hot giant planet, KELT-9b, receives enough ultraviolet radiation for molecular dissociation, with a day-side temperature of ~4,600K. An alternative approach uses irradiated brown dwarfs as hot-Jupiter analogues. With atmospheres and radii similar to those of giant planets, brown dwarfs orbiting close to hot Earth-sized white dwarf stars can be directly detected above the glare of the star.

In this talk I will present the discovery of an extremely irradiated low-mass companion to the hot white dwarf WD0032–317, focusing on the observational aspects of the discovery. Our analysis indicates a day-side temperature of ~8,000K, and a day-to-night temperature difference of ~6,000K. The amount of extreme-ultraviolet radiation received by WD0032–317B is equivalent to that received by planets orbiting close to stars as hot as late B-type stars, and about 5,600 times higher than that of KELT-9b. With a mass of ~75–88 Jupiter masses, this near-hydrogen-burning-limit object is potentially one of the most massive brown dwarfs known.

Simons Observatory (SO) is a new Cosmic Microwave Background telescope currently under construction in the Atacama Desert, close to ALMA and other recent CMB telescopes. It will have six small aperture (42cm) telescopes (SATs), and one large aperture (6m) telescope (LAT), observing at 30-280GHz (1-10mm) using transition edge sensors (TES) and kinetic inductance detectors (KIDs). As well as observing the polarisation of the CMB to unprecedented sensitivity, the LAT will perform a constant survey at higher angular resolution, enabling the systematic detection of transient sources in the submm, with large overlap of optical surveys such as LSST, DESI and DES. As well as giving an overview of SO, I summarise the types of transient sources that are expected to be seen by SO, including flaring stars, quasars, asteroids, and man-made satellites.

El Advanced Instrumentation and Technology Centre (AITC), que forma parte de la Research School of Astronomy and Astrophysics de la Universidad Nacional de Australia, cuenta con un equipo de alrededor de 50 ingenieros e investigadores, tanto de Australia como de diversas partes del mundo, dedicados al desarrollo de instrumentación para telescopios, ya sean terrestres o espaciales.

En esta presentación, la Dra. Noelia Martínez brindará una visión general de los proyectos principales que se están llevando a cabo en el AITC en el marco del programa de óptica adaptativa con estrellas guía láser. El equipo de óptica adaptativa de la ANU trabaja en sistemas aplicados a la astrofísica, la detección de basura espacial y las comunicaciones ópticas. Noelia presentará proyectos que actualmente se encuentran en la fase de diseño final, como el sistema de óptica adaptativa de ground layer para el telescopio Subaru de 8 metros, en Hawaii. En este proyecto, la ANU tiene la responsabilidad del módulo del sensor de frente de onda y de la infraestructura de telescopio para las estrellas guía láser. Además, se abordará el desarrollo del sistema de óptica adaptativa de tomografía láser para el GMT, el telescopio de 25 metros que se instalará en Las Campanas, Chile.

Teniendo en cuenta el crecimiento exponencial del portafolio de proyectos en el programa de investigación de estrellas guía láser, Noelia busca aprovechar esta oportunidad para explorar áreas de colaboración entre los investigadores e ingenieros del IAC y de la ANU.

Youtube

https://www.youtube.com/watch?v=VZsJv78yMks

Astronomy has traditionally been an open science with a wide-spread attitude of sharing and exchange of best practices. Outside of astronomy, a strong movement towards Open Access Publishing has taken place during recent years, which is now affecting all scientific subject areas.

In this presentation, we will give a quick overview of what Open Access is and what it means for astronomy, and will review the current publishing models of core astronomy journals. A special focus will be the support libraries provide to scientists to make the best use of the Open Access options available to them, as well as the ways in which librarians help to shape movements in scholarly communication in order to establish a more collaborative, transparent publishing landscape.

Slurm Workload Manager (formerly known as Simple Linux Utility for Resource Management (SLURM), or simply Slurm, is a free and open-source job scheduler for Linux and Unix-like kernels, used by many of the world's supercomputers and computer clusters.

While Slurm has been used at the IAC in the LaPalma supercomputer and deimos/diva for a long time, we are now starting to also use it in public "burros" (and project burros that request it), in order to ensure
a more efficient and balanced use of these powerful (but shared amongst many users) machines.

While using Slurm is quite easy, we are aware that it involves some changes for users. To help you understand how Slurm works and how to best use it, in this talk I will focus on: why we need queues; an introduction to Slurm usage; Slurm configuration in LaPalma/diva/burros;
use cases (including interactive jobs); ensuring a fair usage amongst users and an efficient use of the machines; etc.

[If you are already a Slurm user and have specific questions/comments, you can post them in the #computing/slurm stream in IAC-Zulip (https://iac-es.zulipchat.com) and I'll try to cover them during the
talk]

MOONS is a 0.8 to 1.8 microns multi-object spectrometer for the Nasmyth focus of UT1 that is being built by a consortium led by the UK-ATC. The instrument is fibre fed, has a multiplex of 1000 and covers a total field of 25 arc minutes in diameter with a high transmission. There are two spectral resolving powers, ~4000 spanning the full wavelength range and a higher resolution mode which gives ~9000 in the I window and ~20,000 in a region in H windows. The instrument itself has two main parts:

• The rotating front-end which is at the focal plane and houses the fibre positioners, acquisition system, metrology system for the fibres, etc., and
• The cryogenic spectrograph which houses the spectrograph optics, VPH gratings and detectors.

MOONS is now approaching completion and is due to be shipped to Paranal in March 2024. This talk presents the MOONS instrument, the science that it will allow, and its current status.

Nebular emission lines are a powerful diagnostic tool for tracing the chemical evolution in star-forming galaxies (SFGs) across cosmic time. Due to their proximity, SGFs are ideal for studying the physical properties, stellar population, and nebular gas in much more detail. The COS Legacy Spectroscopy SurveY (CLASSY) is a treasury survey that comprises UV+optical spectra of 45 local SFGs covering a broad range of physical properties. In this talk, I present the results of the physical conditions and metallicities for the CLASSY sample focused on the impact of the aperture effects of the inferred metallicities and the abundance patterns of several elements. We found that the results for the inferred electron density, temperature, and metallicity derived using different aperture sizes, 1″-3″, are consistent, indicating a uniform mapping of the nebular gas. We also showed that the physical properties derived from the optical are appropriate for observations in the far-UV, allowing a better interpretation of the interplay between the stellar and gas components. I will also discuss the results of the Ne/O, Cl/O, S/O, and Ar/O vs. O/H relations and their behaviour with different galaxy properties (e.g., stellar mass and star formation rate). We found that such abundance ratios follow a constant trend with O/H as expected, except for Ne/O and Ar/O, which show a significant trend at high metallicities. We discuss the scatter involved in the N/O versus O/H relation and its connection with the different UV+optical observables. Finally, we compare these results with the chemical abundances derived at z > 6 galaxies observed with the JWST.

Se profundizará sobre las tres funcionalidades para el sistema de control del IAC80 en las que se ha trabajado durante el periodo de las prácticas externas en el IAC. 

Youtube

https://youtube.com/live/l3J7pRrcuFc?feature=share

La trazabilidad al sistema internacional de unidades SI de las mediciones espectrorradiométricas de la radiación óptica en multitud de aplicaciones (control de variables climáticas esenciales, procesos industriales, iluminación, asistencia sanitaria, seguridad laboral, generación de energía fotovoltaica, etc.) se ha realizado mediante patrones de transferencia basadas en lámparas de incandescencia. Sin embargo, la disponibilidad de estas lámparas está disminuyendo debido al abandono progresivo de la producción de lámparas de este tipo para la iluminación.

El objetivo de este seminario es discutir sobre otras fuentes de radiación (actuales o futuras) que puedan sustituir de forma adecuada y asequible a las lámparas de incandescencia y sobre procedimientos alternativos a las fuentes de radiación para la transferencia/calibración de medidas de irradiancia espectral en los intervalos ultravioleta, visible e infrarrojo cercano.

Youtube:

https://youtube.com/live/T9uHYGMDIAw?feature=share

Extremely metal-poor or zero-metallicity very massive stars, with initial mass in the range 100 ≲ Mi/M⊙ ≲ 1000, have a broad astrophysical impact. Understanding how these population III stars evolve and die has implications for several key questions, including the nature of energetic transients such as pair-instability supernovæ and gamma-ray bursts, the source of extreme ionizing UV-radiation fields at high redshifts, the earliest chemical enrichment of their host galaxies and the rates of gravitational-wave emission from merging black holes among others. There are not many models in literature that follow the evolution of these population III stars, and even less so that reach the phases where the production of electron-positron pairs alter the stability of the whole star. We present new evolutionary models of very massive primordial stars, with initial masses ranging from 100 M☉ to 1000 M☉, that extend from the main sequence until the onset of dynamical instability. We focus on the final outcome of the models and associated compact remnants. Stars that avoid the pair-instability supernova channel, should produce black holes with masses ranging from ~ 40 M☉ to ~ 1000 M☉. In particular, stars with initial masses of about 100 M☉ could leave black holes of ≃ 85-90 M☉, values consistent with the estimated primary black hole mass of the GW190521 merger event. Overall, these results may contribute to explain future data from next-generation gravitational-wave detectors, such as the Einstein Telescope and Cosmic Explorer, which will have access to as-yet unexplored BH mass range of ~ 10^2-10^4 M☉ in the early universe.