The Hyades stream: evaporated cluster or intrusion from the inner disk?

The nature of the Hyades stream, or Hyades moving group, is a long-standing question of Galactic Astronomy. While it has become widely recognized that the Hercules stream, an unbound group of stars lagging behind galactic rotation and moving outward in the galactic disk, is associated with the outer...

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Autores: Famaey, B., Pont, F., Luri Carrascoso, Xavier., Udry, S., Mayor, M., Jorissen, A.
Tipo de recurso: artículo
Estado:Versión publicada
Fecha de publicación:2007
País:España
Institución:Universidad de Barcelona
Repositorio:Dipòsit Digital de la UB
OAI Identifier:oai:diposit.ub.edu:2445/170954
Acceso en línea:https://hdl.handle.net/2445/170954
Access Level:acceso abierto
Palabra clave:Astrofísica
Galàxies
Cinemàtica galàctica
Astrophysics
Galaxies
Galactic kinematics
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spelling The Hyades stream: evaporated cluster or intrusion from the inner disk?Famaey, B.Pont, F.Luri Carrascoso, Xavier.Udry, S.Mayor, M.Jorissen, A.AstrofísicaGalàxiesCinemàtica galàcticaAstrophysicsGalaxiesGalactic kinematicsThe nature of the Hyades stream, or Hyades moving group, is a long-standing question of Galactic Astronomy. While it has become widely recognized that the Hercules stream, an unbound group of stars lagging behind galactic rotation and moving outward in the galactic disk, is associated with the outer Lindblad resonance of the rotating galactic bar, there is still some debate about the nature of the more prominent low-velocity stream sharing the kinematics of the Hyades open cluster. Is this stream caused by additional non-axisymmetric perturbations of the galactic potential, such as transient or quasi-stationary spiral waves, or by the on-going evaporation of the Hyades cluster? Here, a simple observational test has been designed to determine whether the Hyades stream is primarily composed of coeval stars originating from the Hyades cluster, or of field stars. Using the Geneva-Copenhagen survey of F and G dwarfs, we compare the mass distribution and metallicity of the stream to those of field disk stars. If the Hyades stream is composed of stars trapped at resonance, its mass distribution should obey the present-day mass function (PDMF) of the disk, and its metallicity should reflect its origin in the inner regions of the Galaxy. On the other hand, if it is an evaporated cluster, we expect a different mass distribution, depending on the inital mass function (IMF) of the cluster, and on the proportion of evaporated stars as a function of mass. We find that extreme conditions have to be adopted for the selective evaporation and IMF of the cluster to make the observed mass distribution of the stream only roughly consistent (at a one-sigma level) with the coeval evaporated cluster scenario. The observed mass distribution is in much better agreement with the PDMF of the field. The peculiar metallicity of the stream is inconsistent with that of a field population from the solar neighbourhood trapped in the primordial cluster during its formation process and subsequently evaporated. These observations thus favour a resonant origin for the Hyades stream.EDP Sciences2007info:eu-repo/semantics/articleinfo:eu-repo/semantics/publishedVersionapplication/pdfhttps://hdl.handle.net/2445/170954Articles publicats en revistes (Física Quàntica i Astrofísica)reponame:Dipòsit Digital de la UBinstname:Universidad de BarcelonaInglésReproducció del document publicat a: https://doi.org/10.1051/0004-6361:20065706Astronomy & Astrophysics, 2007, vol. 461, p. 957-962https://doi.org/10.1051/0004-6361:20065706(c) The European Southern Observatory (ESO), 2007info:eu-repo/semantics/openAccessoai:diposit.ub.edu:2445/1709542026-05-27T06:46:51Z
dc.title.none.fl_str_mv The Hyades stream: evaporated cluster or intrusion from the inner disk?
title The Hyades stream: evaporated cluster or intrusion from the inner disk?
spellingShingle The Hyades stream: evaporated cluster or intrusion from the inner disk?
Famaey, B.
Astrofísica
Galàxies
Cinemàtica galàctica
Astrophysics
Galaxies
Galactic kinematics
title_short The Hyades stream: evaporated cluster or intrusion from the inner disk?
title_full The Hyades stream: evaporated cluster or intrusion from the inner disk?
title_fullStr The Hyades stream: evaporated cluster or intrusion from the inner disk?
title_full_unstemmed The Hyades stream: evaporated cluster or intrusion from the inner disk?
title_sort The Hyades stream: evaporated cluster or intrusion from the inner disk?
dc.creator.none.fl_str_mv Famaey, B.
Pont, F.
Luri Carrascoso, Xavier.
Udry, S.
Mayor, M.
Jorissen, A.
author Famaey, B.
author_facet Famaey, B.
Pont, F.
Luri Carrascoso, Xavier.
Udry, S.
Mayor, M.
Jorissen, A.
author_role author
author2 Pont, F.
Luri Carrascoso, Xavier.
Udry, S.
Mayor, M.
Jorissen, A.
author2_role author
author
author
author
author
dc.subject.none.fl_str_mv Astrofísica
Galàxies
Cinemàtica galàctica
Astrophysics
Galaxies
Galactic kinematics
topic Astrofísica
Galàxies
Cinemàtica galàctica
Astrophysics
Galaxies
Galactic kinematics
description The nature of the Hyades stream, or Hyades moving group, is a long-standing question of Galactic Astronomy. While it has become widely recognized that the Hercules stream, an unbound group of stars lagging behind galactic rotation and moving outward in the galactic disk, is associated with the outer Lindblad resonance of the rotating galactic bar, there is still some debate about the nature of the more prominent low-velocity stream sharing the kinematics of the Hyades open cluster. Is this stream caused by additional non-axisymmetric perturbations of the galactic potential, such as transient or quasi-stationary spiral waves, or by the on-going evaporation of the Hyades cluster? Here, a simple observational test has been designed to determine whether the Hyades stream is primarily composed of coeval stars originating from the Hyades cluster, or of field stars. Using the Geneva-Copenhagen survey of F and G dwarfs, we compare the mass distribution and metallicity of the stream to those of field disk stars. If the Hyades stream is composed of stars trapped at resonance, its mass distribution should obey the present-day mass function (PDMF) of the disk, and its metallicity should reflect its origin in the inner regions of the Galaxy. On the other hand, if it is an evaporated cluster, we expect a different mass distribution, depending on the inital mass function (IMF) of the cluster, and on the proportion of evaporated stars as a function of mass. We find that extreme conditions have to be adopted for the selective evaporation and IMF of the cluster to make the observed mass distribution of the stream only roughly consistent (at a one-sigma level) with the coeval evaporated cluster scenario. The observed mass distribution is in much better agreement with the PDMF of the field. The peculiar metallicity of the stream is inconsistent with that of a field population from the solar neighbourhood trapped in the primordial cluster during its formation process and subsequently evaporated. These observations thus favour a resonant origin for the Hyades stream.
publishDate 2007
dc.date.none.fl_str_mv 2007
dc.type.none.fl_str_mv info:eu-repo/semantics/article
info:eu-repo/semantics/publishedVersion
format article
status_str publishedVersion
dc.identifier.none.fl_str_mv https://hdl.handle.net/2445/170954
url https://hdl.handle.net/2445/170954
dc.language.none.fl_str_mv Inglés
language_invalid_str_mv Inglés
dc.relation.none.fl_str_mv Reproducció del document publicat a: https://doi.org/10.1051/0004-6361:20065706
Astronomy & Astrophysics, 2007, vol. 461, p. 957-962
https://doi.org/10.1051/0004-6361:20065706
dc.rights.none.fl_str_mv (c) The European Southern Observatory (ESO), 2007
info:eu-repo/semantics/openAccess
rights_invalid_str_mv (c) The European Southern Observatory (ESO), 2007
eu_rights_str_mv openAccess
dc.format.none.fl_str_mv application/pdf
dc.publisher.none.fl_str_mv EDP Sciences
publisher.none.fl_str_mv EDP Sciences
dc.source.none.fl_str_mv Articles publicats en revistes (Física Quàntica i Astrofísica)
reponame:Dipòsit Digital de la UB
instname:Universidad de Barcelona
instname_str Universidad de Barcelona
reponame_str Dipòsit Digital de la UB
collection Dipòsit Digital de la UB
repository.name.fl_str_mv
repository.mail.fl_str_mv
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score 15,301603

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