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dc.contributor.author
Corsico, Alejandro Hugo  
dc.contributor.author
Romero, Alejandra Daniela  
dc.contributor.author
Althaus, Leandro Gabriel  
dc.contributor.author
García Berro, Enrique  
dc.date.available
2018-04-23T13:36:40Z  
dc.date.issued
2009-07  
dc.identifier.citation
Corsico, Alejandro Hugo; Romero, Alejandra Daniela; Althaus, Leandro Gabriel; García Berro, Enrique; Hot C-rich white dwarfs: testing the transition DB-DQ through pulsations; EDP Sciences; Astronomy and Astrophysics; 506; 7-2009; 835-843  
dc.identifier.issn
0004-6361  
dc.identifier.uri
http://hdl.handle.net/11336/42984  
dc.description.abstract
Context. Hot DQ white dwarfs are a new class of white dwarf stars that were discovered recently within the framework of the SDSS project. There are nine known hot DQ stars, out of a total of several thousands white dwarfs spectroscopically identified. Three hot DQ white dwarfs have been reported to exhibit photometric variability with periods compatible with pulsation g-modes. Aims. We present a nonadiabatic pulsation analysis of carbon-rich hot DQ white dwarf stars. One of our main aims is to test the convective-mixing scenario for the origin of hot DQs by studying their pulsational properties. Methods. Our pulsation study is based on the full evolutionary models of hot DQ white dwarfs developed by Althaus and collaborators, which consistently cover the entire evolution from the born-again stage to the white dwarf cooling track. Specifically, we present a stability analysis of white dwarf models from stages before the blue edge of the DBV instability strip ( ≈ 30 000 K), until the domain of the hot DQ white dwarfs (18 000-24 000 K), including the transition DBhot DQ white dwarf. We explore evolutionary models with M* = 0.585 and M* = 0.87 , and two values of the thickness of the He-rich envelope ( = 210-7 M* and = 10-8 M*). These envelopes are 4–5 orders of magnitude thinner than those of standard DB white dwarf models resulting from canonical stellar evolution computations. Results. We found that at evolutionary phases in which the models are characterized by He-dominated atmospheres, they exhibit unstable g-mode pulsations typical of DBV stars, and when the models become DQ white dwarfs with carbon-dominated atmospheres, they continue being pulsationally unstable with characteristics similar to DB models, and in agreement with the periods detected in variable hot DQ white dwarfs. In particular, for models with = 10-8 M*, a narrow gap exists separating the DB from the DQ instability domains. Conclusions. Our calculations provide strong support for the convective-mixing picture of the formation of hot DQs. In particular, our results suggest the existence of pulsating DB white dwarfs with very thin He-rich envelopes, which after passing the DBV instability strip become variable hot DQ stars. The existence of these DB stars with very thin envelopes should be investigated by asteroseismology.  
dc.format
application/pdf  
dc.language.iso
eng  
dc.publisher
EDP Sciences  
dc.rights
info:eu-repo/semantics/openAccess  
dc.rights.uri
https://creativecommons.org/licenses/by-nc-sa/2.5/ar/  
dc.subject
Evolution of Stars  
dc.subject
Interior Stars  
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Oscillations  
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White Dwarfs  
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Astronomía  
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Ciencias Físicas  
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CIENCIAS NATURALES Y EXACTAS  
dc.title
Hot C-rich white dwarfs: testing the transition DB-DQ through pulsations  
dc.type
info:eu-repo/semantics/article  
dc.type
info:ar-repo/semantics/artículo  
dc.type
info:eu-repo/semantics/publishedVersion  
dc.date.updated
2018-04-19T18:32:56Z  
dc.journal.volume
506  
dc.journal.pagination
835-843  
dc.journal.pais
Francia  
dc.journal.ciudad
Les Ulis  
dc.description.fil
Fil: Corsico, Alejandro Hugo. Universidad Nacional de La Plata. Facultad de Ciencias Astronómicas y Geofísicas; Argentina. Consejo Nacional de Investigaciones Científicas y Técnicas. Centro Científico Tecnológico Conicet - La Plata. Instituto de Astrofísica La Plata. Universidad Nacional de La Plata. Facultad de Ciencias Astronómicas y Geofísicas. Instituto de Astrofísica La Plata; Argentina  
dc.description.fil
Fil: Romero, Alejandra Daniela. Universidad Nacional de La Plata. Facultad de Ciencias Astronómicas y Geofísicas; Argentina. Consejo Nacional de Investigaciones Científicas y Técnicas. Centro Científico Tecnológico Conicet - La Plata. Instituto de Astrofísica La Plata. Universidad Nacional de La Plata. Facultad de Ciencias Astronómicas y Geofísicas. Instituto de Astrofísica La Plata; Argentina  
dc.description.fil
Fil: Althaus, Leandro Gabriel. Universidad Nacional de La Plata. Facultad de Ciencias Astronómicas y Geofísicas; Argentina. Universidad Politécnica de Catalunya; España  
dc.description.fil
Fil: García Berro, Enrique. Universidad Politécnica de Catalunya; España  
dc.journal.title
Astronomy and Astrophysics  
dc.relation.alternativeid
info:eu-repo/semantics/altIdentifier/doi/http://dx.doi.org/10.1051/0004-6361/200912481  
dc.relation.alternativeid
info:eu-repo/semantics/altIdentifier/url/https://www.aanda.org/articles/aa/abs/2009/41/aa12481-09/aa12481-09.html