Ages of the bulge globular clusters NGC 6522 and NGC 6626 (M28) from HST proper-motion-cleaned color–magnitude diagrams
Autor(a) principal: | |
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Data de Publicação: | 2018 |
Outros Autores: | , , , , , , |
Tipo de documento: | Artigo |
Idioma: | eng |
Título da fonte: | Repositório Institucional da UFRGS |
Texto Completo: | http://hdl.handle.net/10183/178293 |
Resumo: | Bulge globular clusters (GCs) with metallicities [Fe/H]−1.0 and blue horizontal branches are candidates to harbor the oldest populations in the Galaxy. Based on the analysis of HST proper-motion-cleaned color–magnitude diagrams in filters F435W and F625W, we determine physical parameters for the old bulge GCs NGC 6522 and NGC 6626 (M28), both with well-defined blue horizontal branches. We compare these results with similar data for the inner halo cluster NGC 6362. These clusters have similar metallicities (−1.3[Fe/H]−1.0) obtained from high-resolution spectroscopy. We derive ages, distance moduli, and reddening values by means of statistical comparisons between observed and synthetic fiducial lines employing likelihood statistics and the Markov chain Monte Carlo method. The synthetic fiducial lines were generated using α-enhanced BaSTI and Dartmouth stellar evolutionary models, adopting both canonical (Y∼0.25) and enhanced (Y∼0.30–0.33) helium abundances. RR Lyrae stars were employed to determine the HB magnitude level, providing an independent indicator to constrain the apparent distance modulus and the helium enhancement. The shape of the observed fiducial line could be compatible with some helium enhancement for NGC 6522 and NGC 6626, but the average magnitudes of RR Lyrae stars tend to rule out this hypothesis. Assuming canonical helium abundances, BaSTI and Dartmouth models indicate that all three clusters are coeval, with ages between ∼12.5 and 13.0 Gyr. The present study also reveals that NGC 6522 has at least two stellar populations, since its CMD shows a significantly wide subgiant branch compatible with 14%±2% and 86%±5% for first and second generations, respectively. |
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Kerber, Leandro de OliveiraNardiello, DomenicoOrtolani, SergioBarbuy, BeatrizBica, Eduardo Luiz DamianiCassisi, SantiLibralato, MattiaVieira, Rodrigo G.2018-05-17T02:25:30Z20180004-637Xhttp://hdl.handle.net/10183/178293001061770Bulge globular clusters (GCs) with metallicities [Fe/H]−1.0 and blue horizontal branches are candidates to harbor the oldest populations in the Galaxy. Based on the analysis of HST proper-motion-cleaned color–magnitude diagrams in filters F435W and F625W, we determine physical parameters for the old bulge GCs NGC 6522 and NGC 6626 (M28), both with well-defined blue horizontal branches. We compare these results with similar data for the inner halo cluster NGC 6362. These clusters have similar metallicities (−1.3[Fe/H]−1.0) obtained from high-resolution spectroscopy. We derive ages, distance moduli, and reddening values by means of statistical comparisons between observed and synthetic fiducial lines employing likelihood statistics and the Markov chain Monte Carlo method. The synthetic fiducial lines were generated using α-enhanced BaSTI and Dartmouth stellar evolutionary models, adopting both canonical (Y∼0.25) and enhanced (Y∼0.30–0.33) helium abundances. RR Lyrae stars were employed to determine the HB magnitude level, providing an independent indicator to constrain the apparent distance modulus and the helium enhancement. The shape of the observed fiducial line could be compatible with some helium enhancement for NGC 6522 and NGC 6626, but the average magnitudes of RR Lyrae stars tend to rule out this hypothesis. Assuming canonical helium abundances, BaSTI and Dartmouth models indicate that all three clusters are coeval, with ages between ∼12.5 and 13.0 Gyr. The present study also reveals that NGC 6522 has at least two stellar populations, since its CMD shows a significantly wide subgiant branch compatible with 14%±2% and 86%±5% for first and second generations, respectively.application/pdfengThe astrophysical journal. Bristol. Vol. 853, no. 1 (Jan. 2018), 15, 18 p.Aglomerados globularesEvolucao estelarMetalicidadePopulacoes estelaresGlobular clusters: generalGlobular clusters: individual (NGC 6522, NGC 6626, NGC 6362)Ages of the bulge globular clusters NGC 6522 and NGC 6626 (M28) from HST proper-motion-cleaned color–magnitude diagramsEstrangeiroinfo:eu-repo/semantics/articleinfo:eu-repo/semantics/publishedVersioninfo:eu-repo/semantics/openAccessreponame:Repositório Institucional da UFRGSinstname:Universidade Federal do Rio Grande do Sul (UFRGS)instacron:UFRGSORIGINAL001061770.pdf001061770.pdfTexto completo (inglês)application/pdf10641463http://www.lume.ufrgs.br/bitstream/10183/178293/1/001061770.pdf22b4be5339efd638000b09259498446bMD51TEXT001061770.pdf.txt001061770.pdf.txtExtracted Texttext/plain80581http://www.lume.ufrgs.br/bitstream/10183/178293/2/001061770.pdf.txt73c7070c8a683eea85f9639dcaddc4f0MD5210183/1782932023-10-25 03:39:05.27233oai:www.lume.ufrgs.br:10183/178293Repositório de PublicaçõesPUBhttps://lume.ufrgs.br/oai/requestopendoar:2023-10-25T06:39:05Repositório Institucional da UFRGS - Universidade Federal do Rio Grande do Sul (UFRGS)false |
dc.title.pt_BR.fl_str_mv |
Ages of the bulge globular clusters NGC 6522 and NGC 6626 (M28) from HST proper-motion-cleaned color–magnitude diagrams |
title |
Ages of the bulge globular clusters NGC 6522 and NGC 6626 (M28) from HST proper-motion-cleaned color–magnitude diagrams |
spellingShingle |
Ages of the bulge globular clusters NGC 6522 and NGC 6626 (M28) from HST proper-motion-cleaned color–magnitude diagrams Kerber, Leandro de Oliveira Aglomerados globulares Evolucao estelar Metalicidade Populacoes estelares Globular clusters: general Globular clusters: individual (NGC 6522, NGC 6626, NGC 6362) |
title_short |
Ages of the bulge globular clusters NGC 6522 and NGC 6626 (M28) from HST proper-motion-cleaned color–magnitude diagrams |
title_full |
Ages of the bulge globular clusters NGC 6522 and NGC 6626 (M28) from HST proper-motion-cleaned color–magnitude diagrams |
title_fullStr |
Ages of the bulge globular clusters NGC 6522 and NGC 6626 (M28) from HST proper-motion-cleaned color–magnitude diagrams |
title_full_unstemmed |
Ages of the bulge globular clusters NGC 6522 and NGC 6626 (M28) from HST proper-motion-cleaned color–magnitude diagrams |
title_sort |
Ages of the bulge globular clusters NGC 6522 and NGC 6626 (M28) from HST proper-motion-cleaned color–magnitude diagrams |
author |
Kerber, Leandro de Oliveira |
author_facet |
Kerber, Leandro de Oliveira Nardiello, Domenico Ortolani, Sergio Barbuy, Beatriz Bica, Eduardo Luiz Damiani Cassisi, Santi Libralato, Mattia Vieira, Rodrigo G. |
author_role |
author |
author2 |
Nardiello, Domenico Ortolani, Sergio Barbuy, Beatriz Bica, Eduardo Luiz Damiani Cassisi, Santi Libralato, Mattia Vieira, Rodrigo G. |
author2_role |
author author author author author author author |
dc.contributor.author.fl_str_mv |
Kerber, Leandro de Oliveira Nardiello, Domenico Ortolani, Sergio Barbuy, Beatriz Bica, Eduardo Luiz Damiani Cassisi, Santi Libralato, Mattia Vieira, Rodrigo G. |
dc.subject.por.fl_str_mv |
Aglomerados globulares Evolucao estelar Metalicidade Populacoes estelares |
topic |
Aglomerados globulares Evolucao estelar Metalicidade Populacoes estelares Globular clusters: general Globular clusters: individual (NGC 6522, NGC 6626, NGC 6362) |
dc.subject.eng.fl_str_mv |
Globular clusters: general Globular clusters: individual (NGC 6522, NGC 6626, NGC 6362) |
description |
Bulge globular clusters (GCs) with metallicities [Fe/H]−1.0 and blue horizontal branches are candidates to harbor the oldest populations in the Galaxy. Based on the analysis of HST proper-motion-cleaned color–magnitude diagrams in filters F435W and F625W, we determine physical parameters for the old bulge GCs NGC 6522 and NGC 6626 (M28), both with well-defined blue horizontal branches. We compare these results with similar data for the inner halo cluster NGC 6362. These clusters have similar metallicities (−1.3[Fe/H]−1.0) obtained from high-resolution spectroscopy. We derive ages, distance moduli, and reddening values by means of statistical comparisons between observed and synthetic fiducial lines employing likelihood statistics and the Markov chain Monte Carlo method. The synthetic fiducial lines were generated using α-enhanced BaSTI and Dartmouth stellar evolutionary models, adopting both canonical (Y∼0.25) and enhanced (Y∼0.30–0.33) helium abundances. RR Lyrae stars were employed to determine the HB magnitude level, providing an independent indicator to constrain the apparent distance modulus and the helium enhancement. The shape of the observed fiducial line could be compatible with some helium enhancement for NGC 6522 and NGC 6626, but the average magnitudes of RR Lyrae stars tend to rule out this hypothesis. Assuming canonical helium abundances, BaSTI and Dartmouth models indicate that all three clusters are coeval, with ages between ∼12.5 and 13.0 Gyr. The present study also reveals that NGC 6522 has at least two stellar populations, since its CMD shows a significantly wide subgiant branch compatible with 14%±2% and 86%±5% for first and second generations, respectively. |
publishDate |
2018 |
dc.date.accessioned.fl_str_mv |
2018-05-17T02:25:30Z |
dc.date.issued.fl_str_mv |
2018 |
dc.type.driver.fl_str_mv |
Estrangeiro info:eu-repo/semantics/article |
dc.type.status.fl_str_mv |
info:eu-repo/semantics/publishedVersion |
format |
article |
status_str |
publishedVersion |
dc.identifier.uri.fl_str_mv |
http://hdl.handle.net/10183/178293 |
dc.identifier.issn.pt_BR.fl_str_mv |
0004-637X |
dc.identifier.nrb.pt_BR.fl_str_mv |
001061770 |
identifier_str_mv |
0004-637X 001061770 |
url |
http://hdl.handle.net/10183/178293 |
dc.language.iso.fl_str_mv |
eng |
language |
eng |
dc.relation.ispartof.pt_BR.fl_str_mv |
The astrophysical journal. Bristol. Vol. 853, no. 1 (Jan. 2018), 15, 18 p. |
dc.rights.driver.fl_str_mv |
info:eu-repo/semantics/openAccess |
eu_rights_str_mv |
openAccess |
dc.format.none.fl_str_mv |
application/pdf |
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