Accretion from debris disks onto white dwarfs. Fingering (thermohaline) instability and derived accretion rates

Autores
Deal, M.; Deheuvels, S.; Vauclair, G.; Vauclair, S.; Wachlin, Felipe Carlos
Año de publicación
2013
Idioma
inglés
Tipo de recurso
artículo
Estado
versión publicada
Descripción
Context. Recent observations of a large number of DA and DB white dwarfs show evidence of debris disks, which are the remnants of old planetary systems. The infrared excess detected with Spitzer and the lines of heavy elements observed in their atmospheres with high-resolution spectroscopy converge on the idea that planetary material accretes onto these stars. Accretion rates have been derived by several authors with the assumption of a steady state between accretion and gravitational settling. The results are unrealistically different for DA and DB white dwarfs. Aims. When heavy matter is accreted onto stars, it induces an inverse μ-gradient that leads to fingering (thermohaline) convection. The aim of this letter is to study the impact of this specific process on the derived accretion rates in white dwarfs and on the difference between DA and DB. Methods. We solve the diffusion equation for the accreted heavy elements with a time-dependent method. The models we use have been obtained both with the IRAP code, which computes static models, and the La Plata code, which computes evolutionary sequences. Computations with pure gravitational settling are compared with computations that include fingering convection. Results. The most important result is that fingering convection has very important effects on DAs but is inefficient in DBs. When only gravitational settling is taken into account, the time-dependent computations lead to a steady state, as postulated by previous authors. When fingering convection is added, this steady state occurs much later. Conclusions. The surprising difference found in the past for the accretion rates derived for DA and DB white dwarfs disappears. The derived accretion rates for DAs are increased when fingering convection is taken into account, whereas those for DBs are not modified. More precise and developed results will be given in a forthcoming paper
Fil: Deal, M.. Université de Toulouse; Francia
Fil: Deheuvels, S.. Université de Toulouse; Francia
Fil: Vauclair, G.. Université de Toulouse; Francia
Fil: Vauclair, S.. Université de Toulouse; Francia
Fil: Wachlin, Felipe Carlos. 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
Materia
White dwarfs
Planetary systems
Accretion disks
Convection
Diffusion
Hydrodynamics
Nivel de accesibilidad
acceso abierto
Condiciones de uso
https://creativecommons.org/licenses/by-nc-sa/2.5/ar/
Repositorio
CONICET Digital (CONICET)
Institución
Consejo Nacional de Investigaciones Científicas y Técnicas
OAI Identificador
oai:ri.conicet.gov.ar:11336/8524

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network_name_str CONICET Digital (CONICET)
spelling Accretion from debris disks onto white dwarfs. Fingering (thermohaline) instability and derived accretion ratesDeal, M.Deheuvels, S.Vauclair, G.Vauclair, S.Wachlin, Felipe CarlosWhite dwarfsPlanetary systemsAccretion disksConvectionDiffusionHydrodynamicshttps://purl.org/becyt/ford/1.7https://purl.org/becyt/ford/1https://purl.org/becyt/ford/1.7https://purl.org/becyt/ford/1Context. Recent observations of a large number of DA and DB white dwarfs show evidence of debris disks, which are the remnants of old planetary systems. The infrared excess detected with Spitzer and the lines of heavy elements observed in their atmospheres with high-resolution spectroscopy converge on the idea that planetary material accretes onto these stars. Accretion rates have been derived by several authors with the assumption of a steady state between accretion and gravitational settling. The results are unrealistically different for DA and DB white dwarfs. Aims. When heavy matter is accreted onto stars, it induces an inverse μ-gradient that leads to fingering (thermohaline) convection. The aim of this letter is to study the impact of this specific process on the derived accretion rates in white dwarfs and on the difference between DA and DB. Methods. We solve the diffusion equation for the accreted heavy elements with a time-dependent method. The models we use have been obtained both with the IRAP code, which computes static models, and the La Plata code, which computes evolutionary sequences. Computations with pure gravitational settling are compared with computations that include fingering convection. Results. The most important result is that fingering convection has very important effects on DAs but is inefficient in DBs. When only gravitational settling is taken into account, the time-dependent computations lead to a steady state, as postulated by previous authors. When fingering convection is added, this steady state occurs much later. Conclusions. The surprising difference found in the past for the accretion rates derived for DA and DB white dwarfs disappears. The derived accretion rates for DAs are increased when fingering convection is taken into account, whereas those for DBs are not modified. More precise and developed results will be given in a forthcoming paperFil: Deal, M.. Université de Toulouse; FranciaFil: Deheuvels, S.. Université de Toulouse; FranciaFil: Vauclair, G.. Université de Toulouse; FranciaFil: Vauclair, S.. Université de Toulouse; FranciaFil: Wachlin, Felipe Carlos. 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; ArgentinaEdp Sciences2013-09info:eu-repo/semantics/articleinfo:eu-repo/semantics/publishedVersionhttp://purl.org/coar/resource_type/c_6501info:ar-repo/semantics/articuloapplication/pdfapplication/pdfhttp://hdl.handle.net/11336/8524Deal, M.; Deheuvels, S.; Vauclair, G.; Vauclair, S.; Wachlin, Felipe Carlos; Accretion from debris disks onto white dwarfs. Fingering (thermohaline) instability and derived accretion rates; Edp Sciences; Astronomy And Astrophysics; 557; 4; 9-2013; 1-40004-6361enginfo:eu-repo/semantics/altIdentifier/url/http://www.aanda.org/articles/aa/abs/2013/09/aa22206-13/aa22206-13.htmlinfo:eu-repo/semantics/altIdentifier/doi/10.1051/0004-6361/201322206info:eu-repo/semantics/openAccesshttps://creativecommons.org/licenses/by-nc-sa/2.5/ar/reponame:CONICET Digital (CONICET)instname:Consejo Nacional de Investigaciones Científicas y Técnicas2025-09-29T10:34:24Zoai:ri.conicet.gov.ar:11336/8524instacron: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 10:34:24.911CONICET Digital (CONICET) - Consejo Nacional de Investigaciones Científicas y Técnicasfalse
dc.title.none.fl_str_mv Accretion from debris disks onto white dwarfs. Fingering (thermohaline) instability and derived accretion rates
title Accretion from debris disks onto white dwarfs. Fingering (thermohaline) instability and derived accretion rates
spellingShingle Accretion from debris disks onto white dwarfs. Fingering (thermohaline) instability and derived accretion rates
Deal, M.
White dwarfs
Planetary systems
Accretion disks
Convection
Diffusion
Hydrodynamics
title_short Accretion from debris disks onto white dwarfs. Fingering (thermohaline) instability and derived accretion rates
title_full Accretion from debris disks onto white dwarfs. Fingering (thermohaline) instability and derived accretion rates
title_fullStr Accretion from debris disks onto white dwarfs. Fingering (thermohaline) instability and derived accretion rates
title_full_unstemmed Accretion from debris disks onto white dwarfs. Fingering (thermohaline) instability and derived accretion rates
title_sort Accretion from debris disks onto white dwarfs. Fingering (thermohaline) instability and derived accretion rates
dc.creator.none.fl_str_mv Deal, M.
Deheuvels, S.
Vauclair, G.
Vauclair, S.
Wachlin, Felipe Carlos
author Deal, M.
author_facet Deal, M.
Deheuvels, S.
Vauclair, G.
Vauclair, S.
Wachlin, Felipe Carlos
author_role author
author2 Deheuvels, S.
Vauclair, G.
Vauclair, S.
Wachlin, Felipe Carlos
author2_role author
author
author
author
dc.subject.none.fl_str_mv White dwarfs
Planetary systems
Accretion disks
Convection
Diffusion
Hydrodynamics
topic White dwarfs
Planetary systems
Accretion disks
Convection
Diffusion
Hydrodynamics
purl_subject.fl_str_mv https://purl.org/becyt/ford/1.7
https://purl.org/becyt/ford/1
https://purl.org/becyt/ford/1.7
https://purl.org/becyt/ford/1
dc.description.none.fl_txt_mv Context. Recent observations of a large number of DA and DB white dwarfs show evidence of debris disks, which are the remnants of old planetary systems. The infrared excess detected with Spitzer and the lines of heavy elements observed in their atmospheres with high-resolution spectroscopy converge on the idea that planetary material accretes onto these stars. Accretion rates have been derived by several authors with the assumption of a steady state between accretion and gravitational settling. The results are unrealistically different for DA and DB white dwarfs. Aims. When heavy matter is accreted onto stars, it induces an inverse μ-gradient that leads to fingering (thermohaline) convection. The aim of this letter is to study the impact of this specific process on the derived accretion rates in white dwarfs and on the difference between DA and DB. Methods. We solve the diffusion equation for the accreted heavy elements with a time-dependent method. The models we use have been obtained both with the IRAP code, which computes static models, and the La Plata code, which computes evolutionary sequences. Computations with pure gravitational settling are compared with computations that include fingering convection. Results. The most important result is that fingering convection has very important effects on DAs but is inefficient in DBs. When only gravitational settling is taken into account, the time-dependent computations lead to a steady state, as postulated by previous authors. When fingering convection is added, this steady state occurs much later. Conclusions. The surprising difference found in the past for the accretion rates derived for DA and DB white dwarfs disappears. The derived accretion rates for DAs are increased when fingering convection is taken into account, whereas those for DBs are not modified. More precise and developed results will be given in a forthcoming paper
Fil: Deal, M.. Université de Toulouse; Francia
Fil: Deheuvels, S.. Université de Toulouse; Francia
Fil: Vauclair, G.. Université de Toulouse; Francia
Fil: Vauclair, S.. Université de Toulouse; Francia
Fil: Wachlin, Felipe Carlos. 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
description Context. Recent observations of a large number of DA and DB white dwarfs show evidence of debris disks, which are the remnants of old planetary systems. The infrared excess detected with Spitzer and the lines of heavy elements observed in their atmospheres with high-resolution spectroscopy converge on the idea that planetary material accretes onto these stars. Accretion rates have been derived by several authors with the assumption of a steady state between accretion and gravitational settling. The results are unrealistically different for DA and DB white dwarfs. Aims. When heavy matter is accreted onto stars, it induces an inverse μ-gradient that leads to fingering (thermohaline) convection. The aim of this letter is to study the impact of this specific process on the derived accretion rates in white dwarfs and on the difference between DA and DB. Methods. We solve the diffusion equation for the accreted heavy elements with a time-dependent method. The models we use have been obtained both with the IRAP code, which computes static models, and the La Plata code, which computes evolutionary sequences. Computations with pure gravitational settling are compared with computations that include fingering convection. Results. The most important result is that fingering convection has very important effects on DAs but is inefficient in DBs. When only gravitational settling is taken into account, the time-dependent computations lead to a steady state, as postulated by previous authors. When fingering convection is added, this steady state occurs much later. Conclusions. The surprising difference found in the past for the accretion rates derived for DA and DB white dwarfs disappears. The derived accretion rates for DAs are increased when fingering convection is taken into account, whereas those for DBs are not modified. More precise and developed results will be given in a forthcoming paper
publishDate 2013
dc.date.none.fl_str_mv 2013-09
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/11336/8524
Deal, M.; Deheuvels, S.; Vauclair, G.; Vauclair, S.; Wachlin, Felipe Carlos; Accretion from debris disks onto white dwarfs. Fingering (thermohaline) instability and derived accretion rates; Edp Sciences; Astronomy And Astrophysics; 557; 4; 9-2013; 1-4
0004-6361
url http://hdl.handle.net/11336/8524
identifier_str_mv Deal, M.; Deheuvels, S.; Vauclair, G.; Vauclair, S.; Wachlin, Felipe Carlos; Accretion from debris disks onto white dwarfs. Fingering (thermohaline) instability and derived accretion rates; Edp Sciences; Astronomy And Astrophysics; 557; 4; 9-2013; 1-4
0004-6361
dc.language.none.fl_str_mv eng
language eng
dc.relation.none.fl_str_mv info:eu-repo/semantics/altIdentifier/url/http://www.aanda.org/articles/aa/abs/2013/09/aa22206-13/aa22206-13.html
info:eu-repo/semantics/altIdentifier/doi/10.1051/0004-6361/201322206
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
dc.publisher.none.fl_str_mv Edp Sciences
publisher.none.fl_str_mv Edp Sciences
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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