Lyman-alpha wing absorption in cool white dwarf stars
- Autores
- Rohrmann, Rene Daniel; Althaus, Leandro Gabriel; Kepler, S. O.
- Año de publicación
- 2011
- Idioma
- inglés
- Tipo de recurso
- artículo
- Estado
- versión publicada
- Descripción
- 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.
Fil: Rohrmann, Rene Daniel. Consejo Nacional de Investigaciones CientiÂficas y Tecnicas. Centro Cientifico Tecnologico San Juan. Instituto de Ciencias Astronomicas de la Tierra y del Espacio; Argentina
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
Fil: Kepler, S. O.. Universidade Federal do Rio Grande do Sul; Brasil - Materia
-
Absortion lines
Atmospheres of stars
Atomic processes
Molecular processes
White dwarfs - Nivel de accesibilidad
- acceso abierto
- Condiciones de uso
- https://creativecommons.org/licenses/by-nc-sa/2.5/ar/
- Repositorio
- Institución
- Consejo Nacional de Investigaciones Científicas y Técnicas
- OAI Identificador
- oai:ri.conicet.gov.ar:11336/9712
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Lyman-alpha wing absorption in cool white dwarf starsRohrmann, Rene DanielAlthaus, Leandro GabrielKepler, S. O.Absortion linesAtmospheres of starsAtomic processesMolecular processesWhite dwarfshttps://purl.org/becyt/ford/1.3https://purl.org/becyt/ford/1Kowalski & 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.Fil: Rohrmann, Rene Daniel. Consejo Nacional de Investigaciones CientiÂficas y Tecnicas. Centro Cientifico Tecnologico San Juan. Instituto de Ciencias Astronomicas de la Tierra y del Espacio; ArgentinaFil: 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; ArgentinaFil: Kepler, S. O.. Universidade Federal do Rio Grande do Sul; BrasilWiley2011-02info:eu-repo/semantics/articleinfo:eu-repo/semantics/publishedVersionhttp://purl.org/coar/resource_type/c_6501info:ar-repo/semantics/articuloapplication/pdfapplication/pdfapplication/pdfhttp://hdl.handle.net/11336/9712Rohrmann, 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; 781-7910035-8711enginfo:eu-repo/semantics/altIdentifier/arxiv/http://dx.doi.org/10.1111/j.1365-2966.2010.17716.xinfo:eu-repo/semantics/altIdentifier/url/http://mnras.oxfordjournals.org/content/411/2/781info:eu-repo/semantics/openAccesshttps://creativecommons.org/licenses/by-nc-sa/2.5/ar/reponame:CONICET Digital (CONICET)instname:Consejo Nacional de Investigaciones Científicas y Técnicas2025-09-29T09:34:31Zoai:ri.conicet.gov.ar:11336/9712instacron:CONICETInstitucionalhttp://ri.conicet.gov.ar/Organismo científico-tecnológicoNo correspondehttp://ri.conicet.gov.ar/oai/requestdasensio@conicet.gov.ar; lcarlino@conicet.gov.arArgentinaNo correspondeNo correspondeNo correspondeopendoar:34982025-09-29 09:34:32.045CONICET Digital (CONICET) - Consejo Nacional de Investigaciones Científicas y Técnicasfalse |
dc.title.none.fl_str_mv |
Lyman-alpha wing absorption in cool white dwarf stars |
title |
Lyman-alpha wing absorption in cool white dwarf stars |
spellingShingle |
Lyman-alpha wing absorption in cool white dwarf stars Rohrmann, Rene Daniel Absortion lines Atmospheres of stars Atomic processes Molecular processes White dwarfs |
title_short |
Lyman-alpha wing absorption in cool white dwarf stars |
title_full |
Lyman-alpha wing absorption in cool white dwarf stars |
title_fullStr |
Lyman-alpha wing absorption in cool white dwarf stars |
title_full_unstemmed |
Lyman-alpha wing absorption in cool white dwarf stars |
title_sort |
Lyman-alpha wing absorption in cool white dwarf stars |
dc.creator.none.fl_str_mv |
Rohrmann, Rene Daniel Althaus, Leandro Gabriel Kepler, S. O. |
author |
Rohrmann, Rene Daniel |
author_facet |
Rohrmann, Rene Daniel Althaus, Leandro Gabriel Kepler, S. O. |
author_role |
author |
author2 |
Althaus, Leandro Gabriel Kepler, S. O. |
author2_role |
author author |
dc.subject.none.fl_str_mv |
Absortion lines Atmospheres of stars Atomic processes Molecular processes White dwarfs |
topic |
Absortion lines Atmospheres of stars Atomic processes Molecular processes White dwarfs |
purl_subject.fl_str_mv |
https://purl.org/becyt/ford/1.3 https://purl.org/becyt/ford/1 |
dc.description.none.fl_txt_mv |
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. Fil: Rohrmann, Rene Daniel. Consejo Nacional de Investigaciones CientiÂficas y Tecnicas. Centro Cientifico Tecnologico San Juan. Instituto de Ciencias Astronomicas de la Tierra y del Espacio; Argentina 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 Fil: Kepler, S. O.. Universidade Federal do Rio Grande do Sul; Brasil |
description |
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. |
publishDate |
2011 |
dc.date.none.fl_str_mv |
2011-02 |
dc.type.none.fl_str_mv |
info:eu-repo/semantics/article info:eu-repo/semantics/publishedVersion http://purl.org/coar/resource_type/c_6501 info:ar-repo/semantics/articulo |
format |
article |
status_str |
publishedVersion |
dc.identifier.none.fl_str_mv |
http://hdl.handle.net/11336/9712 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 0035-8711 |
url |
http://hdl.handle.net/11336/9712 |
identifier_str_mv |
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 0035-8711 |
dc.language.none.fl_str_mv |
eng |
language |
eng |
dc.relation.none.fl_str_mv |
info:eu-repo/semantics/altIdentifier/arxiv/http://dx.doi.org/10.1111/j.1365-2966.2010.17716.x info:eu-repo/semantics/altIdentifier/url/http://mnras.oxfordjournals.org/content/411/2/781 |
dc.rights.none.fl_str_mv |
info:eu-repo/semantics/openAccess https://creativecommons.org/licenses/by-nc-sa/2.5/ar/ |
eu_rights_str_mv |
openAccess |
rights_invalid_str_mv |
https://creativecommons.org/licenses/by-nc-sa/2.5/ar/ |
dc.format.none.fl_str_mv |
application/pdf application/pdf application/pdf |
dc.publisher.none.fl_str_mv |
Wiley |
publisher.none.fl_str_mv |
Wiley |
dc.source.none.fl_str_mv |
reponame:CONICET Digital (CONICET) instname:Consejo Nacional de Investigaciones Científicas y Técnicas |
reponame_str |
CONICET Digital (CONICET) |
collection |
CONICET Digital (CONICET) |
instname_str |
Consejo Nacional de Investigaciones Científicas y Técnicas |
repository.name.fl_str_mv |
CONICET Digital (CONICET) - Consejo Nacional de Investigaciones Científicas y Técnicas |
repository.mail.fl_str_mv |
dasensio@conicet.gov.ar; lcarlino@conicet.gov.ar |
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1844613068677447680 |
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13.070432 |