Show simple item record Rohrmann, Rene Daniel Althaus, Leandro Gabriel Kepler, S. O. 2016-12-19T15:27:26Z 2011-02
dc.identifier.citation Rohrmann, Rene Daniel; Althaus, Leandro Gabriel; Kepler, S. O.; Lyman-alpha wing absorption in cool white dwarf stars; Wiley; Monthly Notices Of The Royal Astronomical Society; 411; 2-2011; 781-791
dc.identifier.issn 0035-8711
dc.description.abstract Kowalski & Saumon identified the missing absorption mechanism in the observed spectra of cool white dwarf stars as the Lyman α red wing formed by the collisions between atomic and molecular hydrogen and successfully explained entire spectra of many cool DA-type white dwarfs. Owing to the important astrophysical implications of this issue, we present here an independent assessment of the process. For this purpose, we compute free–free quasi-molecular absorption in Lyman α due to collisions with H and H2 within the one-perturber, quasi-static approximation. Line cross-sections are obtained using theoretical molecular potentials to describe the interaction between the radiating atom and the perturber. The variation in the electric dipole transition moment with the interparticle distance is also considered. Six and two allowed electric dipole transitions due to H–H and H–H2 collisions, respectively, are taken into account. The new theoretical Lyman α line profiles are then incorporated in our stellar atmosphere program for the computation of synthetic spectra and colours of DA-type white dwarfs. Illustrative model atmospheres and spectral energy distributions are computed, which show that Lyman α broadening by atoms and molecules has a significant effect on the white dwarf atmosphere models. The inclusion of this collision-induced opacity significantly reddens spectral energy distributions and affects the broad-band colour indices for model atmospheres with Teff < 5000 K. These results confirm those previously obtained by Kowalski & Saumon. Our study points out the need for reliable evaluations of H3 potential energy surfaces covering a large region of nuclear configurations, in order to obtain a better description of H–H2 collisions and a more accurate evaluation of their influence on the spectrum of cool white dwarfs.
dc.format application/pdf
dc.language.iso eng
dc.publisher Wiley
dc.rights info:eu-repo/semantics/openAccess
dc.subject Absortion lines
dc.subject Atmospheres of stars
dc.subject Atomic processes
dc.subject Molecular processes
dc.subject White dwarfs
dc.subject.classification Astronomía
dc.subject.classification Ciencias Físicas
dc.subject.classification CIENCIAS NATURALES Y EXACTAS
dc.title Lyman-alpha wing absorption in cool white dwarf stars
dc.type info:eu-repo/semantics/article
dc.type info:ar-repo/semantics/artículo
dc.type info:eu-repo/semantics/publishedVersion 2016-12-14T15:25:45Z
dc.journal.volume 411
dc.journal.pagination 781-791
dc.journal.pais Reino Unido
dc.journal.ciudad London
dc.description.fil Fil: Rohrmann, Rene Daniel. Consejo Nacional de Investigaciones Cienti­ficas y Tecnicas. Centro Cientifico Tecnologico San Juan. Instituto de Ciencias Astronomicas de la Tierra y del Espacio; Argentina
dc.description.fil Fil: Althaus, Leandro Gabriel. Consejo Nacional de Investigaciones Científicas y Técnicas. Centro Científico Tecnológico La Plata. Instituto de Astrofísica de La Plata; Argentina. Universidad Nacional de la Plata. Facultad de Ciencias Astronómicas y Geofísicas; Argentina
dc.description.fil Fil: Kepler, S. O.. Universidade Federal do Rio Grande do Sul; Brasil
dc.journal.title Monthly Notices Of The Royal Astronomical Society
dc.relation.alternativeid info:eu-repo/semantics/altIdentifier/arxiv/
dc.relation.alternativeid info:eu-repo/semantics/altIdentifier/url/

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info:eu-repo/semantics/openAccess Excepto donde se diga explícitamente, este item se publica bajo la siguiente descripción: Creative Commons Attribution-NonCommercial-ShareAlike 2.5 Unported (CC BY-NC-SA 2.5)