Photometric evidence of an intermediate-age stellar population in the inner bulge of M31

We explore the assembly history of the M31 bulge within a projected major-axis radius of 180 arcsec (~680 pc) by studying its stellar populations in Hubble Space TelescopeWide Field Camera 3 and Advanced Camera for Surveys observations. Colours formed by comparing nearultraviolet versus optical band...

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Autores: Dong, H., Li, Zhiyuan, Wang, Q. Daniel, Lauer, Tod R., Olsen, Knut A. G., Saha, Abhijit, Dalcanton, Julianne J., Williams, Benjamin F.
Tipo de recurso: artículo
Estado:Versión publicada
Fecha de publicación:2015
País:España
Institución:Consejo Superior de Investigaciones Científicas (CSIC)
Repositorio:DIGITAL.CSIC. Repositorio Institucional del CSIC
OAI Identifier:oai:digital.csic.es:10261/389768
Acceso en línea:http://hdl.handle.net/10261/389768
Access Level:acceso abierto
Palabra clave:Galaxies: abundances
Galaxies: bulges
Galaxies: evolution
Galaxies: stellar content
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spelling Photometric evidence of an intermediate-age stellar population in the inner bulge of M31Dong, H.Li, ZhiyuanWang, Q. DanielLauer, Tod R.Olsen, Knut A. G.Saha, AbhijitDalcanton, Julianne J.Williams, Benjamin F.Galaxies: abundancesGalaxies: bulgesGalaxies: evolutionGalaxies: stellar contentWe explore the assembly history of the M31 bulge within a projected major-axis radius of 180 arcsec (~680 pc) by studying its stellar populations in Hubble Space TelescopeWide Field Camera 3 and Advanced Camera for Surveys observations. Colours formed by comparing nearultraviolet versus optical bands are found to become bluer with increasing major-axis radius, which is opposite to that predicted if the sole sources of near-ultraviolet light were old extreme horizontal branch stars with a negative radial gradient in metallicity. Spectral energy distribution fits require a metal-rich intermediate-age stellar population (300 Myr to 1 Gyr old, ~Z<inf>⊙</inf>) in addition to the dominant old population. The radial gradients in age and metallicity of the old stellar population are consistent with those in previous works. For the intermediate-age population, we find an increase in age with radius and a mass fraction that increases up to 2 per cent at 680 pc away from the centre. We exclude contamination from the M31 disc and/or halo as the main origin for this population. Our results thus suggest that intermediate-age stars exist beyond the central 5 arcsec (19 pc) of M31 and contribute ~1 per cent of the total stellar mass in the bulge. These stars could be related to the secular growth of the M31 bulge. © 2015 The Authors Published by Oxford University Press on behalf of the Royal Astronomical Society.This article is based on observations made with the NASA/ESA HST and obtained from the data archive at the Space Telescope Science Institute, which is operated by the Association of Universities for Research in Astronomy, Inc. under NASA contract NAS 5-26555. We are grateful to Philip Rosenfield, Luciana Bianchi, Antonela Monachesi, Morgan Fouesneau for valuable comments and discussion. This work is supported by NASA grant GO-12055 provided by the Space Telescope Science Institute, which is operated by the Association of Universities for Research in Astronomy, Inc., under NASA contract NAS 5-26555. HD acknowledges the support and hospitality of the Key Laboratory of Modern Astronomy and Astrophysics at Nanjing University during his visit, and would like to thank Robert W. O'Connell and Daniela Calzetti for providing the spectrum used in Fig. 1. ZL acknowledges support from the Recruitment Program of Global Youth Experts and the National Natural Science Foundation of China (grant 11133001).Oxford University PressNASANational Natural Science Foundation of ChinaConsejo Superior de Investigaciones Científicas [https://ror.org/02gfc7t72]2025202520152025info:eu-repo/semantics/articlehttp://purl.org/coar/resource_type/c_6501Publisher's versioninfo:eu-repo/semantics/publishedVersionhttp://hdl.handle.net/10261/389768reponame:DIGITAL.CSIC. Repositorio Institucional del CSICinstname:Consejo Superior de Investigaciones Científicas (CSIC)Ingléshttp://dx.doi.org/10.1093/mnras/stv1256Síinfo:eu-repo/semantics/openAccessoai:digital.csic.es:10261/3897682026-05-22T06:33:51Z
dc.title.none.fl_str_mv Photometric evidence of an intermediate-age stellar population in the inner bulge of M31
title Photometric evidence of an intermediate-age stellar population in the inner bulge of M31
spellingShingle Photometric evidence of an intermediate-age stellar population in the inner bulge of M31
Dong, H.
Galaxies: abundances
Galaxies: bulges
Galaxies: evolution
Galaxies: stellar content
title_short Photometric evidence of an intermediate-age stellar population in the inner bulge of M31
title_full Photometric evidence of an intermediate-age stellar population in the inner bulge of M31
title_fullStr Photometric evidence of an intermediate-age stellar population in the inner bulge of M31
title_full_unstemmed Photometric evidence of an intermediate-age stellar population in the inner bulge of M31
title_sort Photometric evidence of an intermediate-age stellar population in the inner bulge of M31
dc.creator.none.fl_str_mv Dong, H.
Li, Zhiyuan
Wang, Q. Daniel
Lauer, Tod R.
Olsen, Knut A. G.
Saha, Abhijit
Dalcanton, Julianne J.
Williams, Benjamin F.
author Dong, H.
author_facet Dong, H.
Li, Zhiyuan
Wang, Q. Daniel
Lauer, Tod R.
Olsen, Knut A. G.
Saha, Abhijit
Dalcanton, Julianne J.
Williams, Benjamin F.
author_role author
author2 Li, Zhiyuan
Wang, Q. Daniel
Lauer, Tod R.
Olsen, Knut A. G.
Saha, Abhijit
Dalcanton, Julianne J.
Williams, Benjamin F.
author2_role author
author
author
author
author
author
author
dc.contributor.none.fl_str_mv NASA
National Natural Science Foundation of China
Consejo Superior de Investigaciones Científicas [https://ror.org/02gfc7t72]
dc.subject.none.fl_str_mv Galaxies: abundances
Galaxies: bulges
Galaxies: evolution
Galaxies: stellar content
topic Galaxies: abundances
Galaxies: bulges
Galaxies: evolution
Galaxies: stellar content
description We explore the assembly history of the M31 bulge within a projected major-axis radius of 180 arcsec (~680 pc) by studying its stellar populations in Hubble Space TelescopeWide Field Camera 3 and Advanced Camera for Surveys observations. Colours formed by comparing nearultraviolet versus optical bands are found to become bluer with increasing major-axis radius, which is opposite to that predicted if the sole sources of near-ultraviolet light were old extreme horizontal branch stars with a negative radial gradient in metallicity. Spectral energy distribution fits require a metal-rich intermediate-age stellar population (300 Myr to 1 Gyr old, ~Z<inf>⊙</inf>) in addition to the dominant old population. The radial gradients in age and metallicity of the old stellar population are consistent with those in previous works. For the intermediate-age population, we find an increase in age with radius and a mass fraction that increases up to 2 per cent at 680 pc away from the centre. We exclude contamination from the M31 disc and/or halo as the main origin for this population. Our results thus suggest that intermediate-age stars exist beyond the central 5 arcsec (19 pc) of M31 and contribute ~1 per cent of the total stellar mass in the bulge. These stars could be related to the secular growth of the M31 bulge. © 2015 The Authors Published by Oxford University Press on behalf of the Royal Astronomical Society.
publishDate 2015
dc.date.none.fl_str_mv 2015
2025
2025
2025
dc.type.none.fl_str_mv info:eu-repo/semantics/article
http://purl.org/coar/resource_type/c_6501
Publisher's version
info:eu-repo/semantics/publishedVersion
format article
status_str publishedVersion
dc.identifier.none.fl_str_mv http://hdl.handle.net/10261/389768
url http://hdl.handle.net/10261/389768
dc.language.none.fl_str_mv Inglés
language_invalid_str_mv Inglés
dc.relation.none.fl_str_mv http://dx.doi.org/10.1093/mnras/stv1256
Sí
dc.rights.none.fl_str_mv info:eu-repo/semantics/openAccess
eu_rights_str_mv openAccess
dc.publisher.none.fl_str_mv Oxford University Press
publisher.none.fl_str_mv Oxford University Press
dc.source.none.fl_str_mv reponame:DIGITAL.CSIC. Repositorio Institucional del CSIC
instname:Consejo Superior de Investigaciones Científicas (CSIC)
instname_str Consejo Superior de Investigaciones Científicas (CSIC)
reponame_str DIGITAL.CSIC. Repositorio Institucional del CSIC
collection DIGITAL.CSIC. Repositorio Institucional del CSIC
repository.name.fl_str_mv
repository.mail.fl_str_mv
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score 15,811543

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