Beitia Antero, Leire

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First Name
Last Name
Beitia Antero
Universidad Complutense de Madrid
Faculty / Institute
Ciencias Matemáticas
Física de la Tierra y Astrofísica
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Now showing 1 - 6 of 6
  • Publication
    High reddening patches in Gaia DR2: possible artifacts or indication of star formation at the edge of the Galactic disk
    (EDP Sciences, 2020) Beitia Antero, Leire; Gómez de Castro, Ana Inés; Fuente Marcos, Raúl de la
    Context. Deep GALEX UV data show that the extreme outskirts of some spiral galaxies are teeming with star formation. Such young stellar populations evolving so far away from the bulk of their host galaxies challenge our overall understanding of how star formation proceeds at galactic scales. It is at present unclear whether our own Milky Way may also exhibit ongoing and recent star formation beyond the conventional edge of the disk (∼15 kpc). Aims. Using Gaia DR2 data, we aim to determine if such a population is present in the Galactic halo, beyond the nominal radius of the Milky Way disk. Methods. We studied the kinematics of Gaia DR2 sources with parallax values between 1/60 and 1/30 milliarcseconds towards two regions that show abnormally high values of extinction and reddening; the results are compared with predictions from GALAXIA Galactic model. We also plotted the color–magnitude (CM) diagrams with heliocentric distances computed inverting the parallaxes, and studied the effects of the large parallax errors by Monte Carlo sampling. Results. The kinematics point towards a Galactic origin for one of the regions, while the provenance of the stars in the other is not clear. A spectroscopic analysis of some of the sources in the first region confirms that they are located in the halo. The CM diagram of the sources suggests that some of them are young.
  • Publication
    A database of synthetic photometry in the GALEX ultraviolet bands for the stellar sources observed with the International Ultraviolet Explorer
    (EDP Sciences) Beitia Antero, Leire; Gómez de Castro, Ana Inés
    The Galaxy Evolution Explorer (GALEX) has produced the largest photometric catalogue of ultraviolet (UV) sources. As such, it has defined the new standard bands for UV photometry: the near UV band (NUV) and the far UV band (FUV). However, due to brightness limits, the GALEX mission has avoided the Galactic plane which is crucial for astrophysical research and future space missions. Aims. The International Ultraviolet Explorer (IUE) satellite obtained 63 755 spectra in the low dispersion mode (�=�� � 300) during its 18-year lifetime. We have derived the photometry in the GALEX bands for the stellar sources in the IUE Archive to extend the GALEX database with observations including the Galactic plane. Methods. Good quality spectra have been selected for the IUE classes of stellar sources. The GALEX FUV and NUV magnitudes have been computed using the GALEX transmission curves, as well as the conversion equations between flux and magnitudes provided by the mission. Results. Consistency between GALEX and IUE synthetic photometries has been tested using white dwarfs (WD) contained in both samples. The non-linear response performance of GALEX inferred from this data agrees with the results from GALEX calibration. The photometric database is made available to the community through the services of the Centre de Données Stellaires at Strasbourg (CDS). The catalogue contains FUV magnitudes for 1628 sources, ranging from FUV = 1.81 to FUV = 18.65 mag. In the NUV band, the catalogue includes observations for 999 stars ranging from NUV = 3.34 to NUV = 17.74 mag. Conclusions. UV photometry for 1490 sources not included in the GALEX AIS GR5 catalogue is provided; most of them are hot (O-A spectral type) stars. The sources in the catalogue are distributed over the full sky, including the Galactic plane.
  • Publication
    Evolution of interstellar dust grains in molecular cloud envelopes: observational imprints and theoretical expectations
    (Universidad Complutense de Madrid, 2021-09-17) Beitia Antero, Leire; Gómez de Castro, Ana Inés
    Star formation takes place inside cold, dense clouds of molecular material (molecularclouds) that experience a hierarchical fragmentation process. Inside these clouds the material organises itself in lamentary structures, with a density increasing at smaller scales where stars are eventually formed. The evolution ofthese clouds is aected by the injection of energy into the system. It is now widely accepted that magnetohydrodynamic turbulence contributes to sustain a molecular cloud against collapse and in consequence, directly inuences the star formation eciency. Magnetic elds, therefore, are a fundamental shaping agent of molecular clouds. The most external layers of these clouds, the so-called molecular cloud envelopes, are partially ionised due to their exposure to the ambient radiation field and hence are eectively coupled to the magnetic field. This coupling favours the propagation of hydromagnetic waves inside the clouds, increasing the turbulent state of the gas...
  • Publication
    Dust growth in molecular cloud envelopes: a numerical approach
    (IOP Publishing, 2021-03) Beitia Antero, Leire; Gómez de Castro, Ana Inés
    Variations in the grain size distribution are to be expected in the interstellar medium (ISM) due to grain growth and destruction. In this work, we present a dust collision model to be implemented inside a magnetohydrodynamical (MHD) code that takes into account grain growth and shattering of charged dust grains of a given composition (silicate or graphite). We integrate this model in the MHD code Athena, and builds on a previous implementation of the dynamics of charged dust grains in the same code. To demonstrate the performance of this coagulation model, we study the variations in the grain size distribution of a single-sized population of dust with radius 0.05 µm inside several dust filaments formed during a 2D MHD simulation. We also consider a realistic dust distribution with sizes ranging from 50 Å to 0.25 µm and analyze both the variations in the size distribution for graphite and silicates, as well as of the far ultraviolet extinction curve. From the obtained results, we conclude that the methodology here presented, based on the MHD evolution of the equation of motion for a charged particle, is optimal for studying the coagulation of charged dust grains in a diffuse regime such as a molecular cloud envelope. Observationally, these variations in the dust size distribution are translated into variations in the far ultraviolet extinction curve, and they are mainly caused by small graphite dust grains.
  • Publication
    Habilidades técnicas (soft skills) de los alumnos de Astrofísica en Grado y Máster
    (2021-01-18) Montes Gutiérrez, David; Castro Rubio, Elisa de; Gómez de Castro, Ana Inés; Canet Varea, Ada; Beitia Antero, Leire; Gómez Marfil, Emilio
    El objetivo principal del proyecto de innovación docente es reforzar las habilidades técnicas (soft skills) de los alumnos de astrofísica del Grado en Física y Matemáticas y del Máster en Astrofísica de la Facultad. De cara a los Trabajos Fin de Grado y a las asignaturas prácticas del Máster, consideramos necesario que los alumnos adquieran un dominio previo de ciertas herramientas para un mejor aprovechamiento de los contenidos y un desarrollo fructífero de los TFG y TFM. En particular, consideramos fundamental la familiarización con entornos UNIX, la capacidad de realizar programas básicos en Python para el tratamiento de datos astronómicos, el manejo de grandes bases de datos y la utilización de software libre para astronomía.
  • Publication
    Formation of dust filaments in the diffuse envelopes of molecular clouds
    (IOP Publishing Ltd, 2021-02) Beitia Antero, Leire; Gómez de Castro, Ana I.; Vallejo Chavarino, Juan C.
    The path to understanding star formation processes begins with the study of the formation of molecular clouds. The outskirts of these clouds are characterized by low column densities that allow the penetration of ultraviolet radiation, resulting in a non-negligible ionization fraction and the charging of the small dust grains that are mixed with the gas; this diffuse phase is then coupled to the ambient magnetic field. Despite the general assumption that dust and gas are tightly correlated, several observational and theoretical studies have reported variations in the dust-to-gas ratio toward diffuse and cold clouds. In this work, we present the implementation of a new charged particles module for analyzing the dust dynamics in molecular cloud envelopes. We study the evolution of a single population of small charged grains (0.05 µm) in the turbulent, magnetized molecular cloud envelope using this module. We show that variations in the dust-to-gas ratio arise due to the coupling of the grains with the magnetic field, forming elongated dust structures decoupled from the gas. This emphasizes the importance of considering the dynamics of charged dust when simulating the different phases of the interstellar medium, especially for star formation studies.