The distance to the young open cluster Westerlund 2

Autores
Carraro, G.; Turner, D.; Majaess, D.; Baume, Gustavo Luis
Año de publicación
2013
Idioma
inglés
Tipo de recurso
artículo
Estado
versión publicada
Descripción
A new X-ray, UBVRIc, and JHKs study of the young cluster Westerlund 2 was undertaken to resolve discrepancies tied to the cluster’s distance. Existing spectroscopic observations for bright cluster members and new multi-band photometry imply a reddening relation toward Westerlund 2 described by EU−B/EB−V = 0.63 + 0.02 EB−V . Variable-extinction analyses for Westerlund 2 and nearby IC 2581 based upon spectroscopic distance moduli and ZAMS fitting yield values of RV = AV/EB−V = 3.88±0.18 and 3.77±0.19, respectively, and confirm prior assertions that anomalous interstellar extinction is widespread throughout Carina. The results were confirmed by applying the color-difference method to UBVRIcJHKs data for 19 spectroscopically observed cluster members, yielding RV = 3.85 ± 0.07. The derived distance to Westerlund 2 of d = 2.85 ± 0.43 kpc places the cluster on the far side of the Carina spiral arm. The cluster’s age is no more than τ ∼ 2 × 106 yr as inferred from the cluster’s brightest stars and an X-ray (Chandra) cleaned analysis of its pre-main-sequence demographic. Four Wolf-Rayet stars in the cluster core and surrounding corona (WR20a, WR20b, WR20c, and WR20aa) are very likely cluster members, and their inferred luminosities are consistent with those of other late-WN stars in open clusters. The color–magnitude diagram for Westerlund 2 also displays a gap at spectral type B0.5 V with associated color spread at higher and lower absolute magnitudes that might be linked to close binary mergers. These features, in conjunction with the evidence for mass loss from the WR stars, may help to explain the high flux of γ-rays, cosmic rays, and X-rays from the direction toward Westerlund 2.
Fil: Carraro, G.. Observatorio Europeo Austral; Chile;
Fil: Turner, D.. Saint Mary’s University. Department of Astronomy and Physics; Canadá;
Fil: Majaess, D.. Saint Mary’s University. Department of Astronomy and Physics; Canadá;
Fil: Baume, Gustavo Luis. Consejo Nacional de Investigaciones Científicas y Técnicas. Centro Científico Tecnológico La Plata. Instituto de Astrofísica La Plata; Argentina;
Materia
Open clusters and associations
Wolf-Rayet
H ii regions
Westerlund 2
Nivel de accesibilidad
acceso abierto
Condiciones de uso
https://creativecommons.org/licenses/by-nc/2.5/ar/
Repositorio
CONICET Digital (CONICET)
Institución
Consejo Nacional de Investigaciones Científicas y Técnicas
OAI Identificador
oai:ri.conicet.gov.ar:11336/2430

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spelling The distance to the young open cluster Westerlund 2Carraro, G.Turner, D.Majaess, D.Baume, Gustavo LuisOpen clusters and associationsWolf-RayetH ii regionsWesterlund 2https://purl.org/becyt/ford/1.3https://purl.org/becyt/ford/1A new X-ray, UBVRIc, and JHKs study of the young cluster Westerlund 2 was undertaken to resolve discrepancies tied to the cluster’s distance. Existing spectroscopic observations for bright cluster members and new multi-band photometry imply a reddening relation toward Westerlund 2 described by EU−B/EB−V = 0.63 + 0.02 EB−V . Variable-extinction analyses for Westerlund 2 and nearby IC 2581 based upon spectroscopic distance moduli and ZAMS fitting yield values of RV = AV/EB−V = 3.88±0.18 and 3.77±0.19, respectively, and confirm prior assertions that anomalous interstellar extinction is widespread throughout Carina. The results were confirmed by applying the color-difference method to UBVRIcJHKs data for 19 spectroscopically observed cluster members, yielding RV = 3.85 ± 0.07. The derived distance to Westerlund 2 of d = 2.85 ± 0.43 kpc places the cluster on the far side of the Carina spiral arm. The cluster’s age is no more than τ ∼ 2 × 106 yr as inferred from the cluster’s brightest stars and an X-ray (Chandra) cleaned analysis of its pre-main-sequence demographic. Four Wolf-Rayet stars in the cluster core and surrounding corona (WR20a, WR20b, WR20c, and WR20aa) are very likely cluster members, and their inferred luminosities are consistent with those of other late-WN stars in open clusters. The color–magnitude diagram for Westerlund 2 also displays a gap at spectral type B0.5 V with associated color spread at higher and lower absolute magnitudes that might be linked to close binary mergers. These features, in conjunction with the evidence for mass loss from the WR stars, may help to explain the high flux of γ-rays, cosmic rays, and X-rays from the direction toward Westerlund 2.Fil: Carraro, G.. Observatorio Europeo Austral; Chile;Fil: Turner, D.. Saint Mary’s University. Department of Astronomy and Physics; Canadá;Fil: Majaess, D.. Saint Mary’s University. Department of Astronomy and Physics; Canadá;Fil: Baume, Gustavo Luis. Consejo Nacional de Investigaciones Científicas y Técnicas. Centro Científico Tecnológico La Plata. Instituto de Astrofísica La Plata; Argentina;EDP Sciences2013-07info:eu-repo/semantics/articleinfo:eu-repo/semantics/publishedVersionhttp://purl.org/coar/resource_type/c_6501info:ar-repo/semantics/articuloapplication/pdfapplication/pdfhttp://hdl.handle.net/11336/2430Carraro, G.; Turner, D.; Majaess, D.; Baume, Gustavo Luis; The distance to the young open cluster Westerlund 2; EDP Sciences; Astronomy & Astrophysics; 555; A50; 7-2013; 1-90004-6361enginfo:eu-repo/semantics/altIdentifier/url/http://www.aanda.org/articles/aa/abs/2013/07/aa21421-13/aa21421-13.htmlinfo:eu-repo/semantics/altIdentifier/url/http://arxiv.org/abs/1305.4309info:eu-repo/semantics/altIdentifier/doi/10.1051/0004-6361/201321421info:eu-repo/semantics/openAccesshttps://creativecommons.org/licenses/by-nc/2.5/ar/reponame:CONICET Digital (CONICET)instname:Consejo Nacional de Investigaciones Científicas y Técnicas2025-10-15T14:22:17Zoai:ri.conicet.gov.ar:11336/2430instacron: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:34982025-10-15 14:22:17.841CONICET Digital (CONICET) - Consejo Nacional de Investigaciones Científicas y Técnicasfalse
dc.title.none.fl_str_mv The distance to the young open cluster Westerlund 2
title The distance to the young open cluster Westerlund 2
spellingShingle The distance to the young open cluster Westerlund 2
Carraro, G.
Open clusters and associations
Wolf-Rayet
H ii regions
Westerlund 2
title_short The distance to the young open cluster Westerlund 2
title_full The distance to the young open cluster Westerlund 2
title_fullStr The distance to the young open cluster Westerlund 2
title_full_unstemmed The distance to the young open cluster Westerlund 2
title_sort The distance to the young open cluster Westerlund 2
dc.creator.none.fl_str_mv Carraro, G.
Turner, D.
Majaess, D.
Baume, Gustavo Luis
author Carraro, G.
author_facet Carraro, G.
Turner, D.
Majaess, D.
Baume, Gustavo Luis
author_role author
author2 Turner, D.
Majaess, D.
Baume, Gustavo Luis
author2_role author
author
author
dc.subject.none.fl_str_mv Open clusters and associations
Wolf-Rayet
H ii regions
Westerlund 2
topic Open clusters and associations
Wolf-Rayet
H ii regions
Westerlund 2
purl_subject.fl_str_mv https://purl.org/becyt/ford/1.3
https://purl.org/becyt/ford/1
dc.description.none.fl_txt_mv A new X-ray, UBVRIc, and JHKs study of the young cluster Westerlund 2 was undertaken to resolve discrepancies tied to the cluster’s distance. Existing spectroscopic observations for bright cluster members and new multi-band photometry imply a reddening relation toward Westerlund 2 described by EU−B/EB−V = 0.63 + 0.02 EB−V . Variable-extinction analyses for Westerlund 2 and nearby IC 2581 based upon spectroscopic distance moduli and ZAMS fitting yield values of RV = AV/EB−V = 3.88±0.18 and 3.77±0.19, respectively, and confirm prior assertions that anomalous interstellar extinction is widespread throughout Carina. The results were confirmed by applying the color-difference method to UBVRIcJHKs data for 19 spectroscopically observed cluster members, yielding RV = 3.85 ± 0.07. The derived distance to Westerlund 2 of d = 2.85 ± 0.43 kpc places the cluster on the far side of the Carina spiral arm. The cluster’s age is no more than τ ∼ 2 × 106 yr as inferred from the cluster’s brightest stars and an X-ray (Chandra) cleaned analysis of its pre-main-sequence demographic. Four Wolf-Rayet stars in the cluster core and surrounding corona (WR20a, WR20b, WR20c, and WR20aa) are very likely cluster members, and their inferred luminosities are consistent with those of other late-WN stars in open clusters. The color–magnitude diagram for Westerlund 2 also displays a gap at spectral type B0.5 V with associated color spread at higher and lower absolute magnitudes that might be linked to close binary mergers. These features, in conjunction with the evidence for mass loss from the WR stars, may help to explain the high flux of γ-rays, cosmic rays, and X-rays from the direction toward Westerlund 2.
Fil: Carraro, G.. Observatorio Europeo Austral; Chile;
Fil: Turner, D.. Saint Mary’s University. Department of Astronomy and Physics; Canadá;
Fil: Majaess, D.. Saint Mary’s University. Department of Astronomy and Physics; Canadá;
Fil: Baume, Gustavo Luis. Consejo Nacional de Investigaciones Científicas y Técnicas. Centro Científico Tecnológico La Plata. Instituto de Astrofísica La Plata; Argentina;
description A new X-ray, UBVRIc, and JHKs study of the young cluster Westerlund 2 was undertaken to resolve discrepancies tied to the cluster’s distance. Existing spectroscopic observations for bright cluster members and new multi-band photometry imply a reddening relation toward Westerlund 2 described by EU−B/EB−V = 0.63 + 0.02 EB−V . Variable-extinction analyses for Westerlund 2 and nearby IC 2581 based upon spectroscopic distance moduli and ZAMS fitting yield values of RV = AV/EB−V = 3.88±0.18 and 3.77±0.19, respectively, and confirm prior assertions that anomalous interstellar extinction is widespread throughout Carina. The results were confirmed by applying the color-difference method to UBVRIcJHKs data for 19 spectroscopically observed cluster members, yielding RV = 3.85 ± 0.07. The derived distance to Westerlund 2 of d = 2.85 ± 0.43 kpc places the cluster on the far side of the Carina spiral arm. The cluster’s age is no more than τ ∼ 2 × 106 yr as inferred from the cluster’s brightest stars and an X-ray (Chandra) cleaned analysis of its pre-main-sequence demographic. Four Wolf-Rayet stars in the cluster core and surrounding corona (WR20a, WR20b, WR20c, and WR20aa) are very likely cluster members, and their inferred luminosities are consistent with those of other late-WN stars in open clusters. The color–magnitude diagram for Westerlund 2 also displays a gap at spectral type B0.5 V with associated color spread at higher and lower absolute magnitudes that might be linked to close binary mergers. These features, in conjunction with the evidence for mass loss from the WR stars, may help to explain the high flux of γ-rays, cosmic rays, and X-rays from the direction toward Westerlund 2.
publishDate 2013
dc.date.none.fl_str_mv 2013-07
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/11336/2430
Carraro, G.; Turner, D.; Majaess, D.; Baume, Gustavo Luis; The distance to the young open cluster Westerlund 2; EDP Sciences; Astronomy & Astrophysics; 555; A50; 7-2013; 1-9
0004-6361
url http://hdl.handle.net/11336/2430
identifier_str_mv Carraro, G.; Turner, D.; Majaess, D.; Baume, Gustavo Luis; The distance to the young open cluster Westerlund 2; EDP Sciences; Astronomy & Astrophysics; 555; A50; 7-2013; 1-9
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/2013/07/aa21421-13/aa21421-13.html
info:eu-repo/semantics/altIdentifier/url/http://arxiv.org/abs/1305.4309
info:eu-repo/semantics/altIdentifier/doi/10.1051/0004-6361/201321421
dc.rights.none.fl_str_mv info:eu-repo/semantics/openAccess
https://creativecommons.org/licenses/by-nc/2.5/ar/
eu_rights_str_mv openAccess
rights_invalid_str_mv https://creativecommons.org/licenses/by-nc/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
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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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