The horizontal branch morphology of M 31 globular clusters Extreme second parameter effect in outer halo clusters

Simple item page
dc.contributor.authorPerina, S.
dc.contributor.authorBellazzini, M.
dc.contributor.authorBuzzoni, A.
dc.contributor.authorCacciari, C.
dc.contributor.authorFederici, L.
dc.contributor.authorPecci, F. Fusi
dc.contributor.authorGalleti, S.
dc.date.accessioned2025-01-24T00:06:58Z
dc.date.available2025-01-24T00:06:58Z
dc.date.issued2012
dc.description.abstractWe use deep, high quality color magnitude diagrams obtained with the Hubble Space Telescope to compute a simplified version of the Mironov index (SMI; B/B+R) to parametrize the horizontal branch (HB) morphology for 23 globular clusters in the M 31 galaxy (Sample A), all located in the outer halo at projected distances between 10 kpc and 100 kpc. This allows us to compare them with their Galactic counterparts, for which we estimated the SMI exactly in the same way, in the SMI vs. [Fe/H] plane. We find that the majority of the considered M 31 clusters lie in a significantly different locus, in this plane, with respect to Galactic clusters lying at any distance from the center of the Milky Way. In particular they have redder HB morphologies at a given metallicity, or, in other words, clusters with the same SMI value are approximate to 0.4 dex more metal rich in the Milky Way than in M 31. We discuss the possible origin of this difference and we conclude that the most likely explanation is that many globular clusters in the outer halo of M 31 formed approximate to 1-2 Gyr later than their counterparts in the outer halo of the Milky Way, while differences in the cluster-to-cluster distribution of He abundance of individual stars may also play a role. The analysis of another sample of 25 bright M 31 clusters (eighteen of them with M-V <= -9.0, Sample B), whose SMI estimates are much more uncertain as they are computed on shallow color magnitude diagrams, suggests that extended blue HB tails can be relatively frequent among the most massive M 31 globular clusters, possibly hinting at the presence of multiple populations.
dc.fuente.origenWOS
dc.identifier.doi10.1051/0004-6361/201220037
dc.identifier.eissn1432-0746
dc.identifier.issn0004-6361
dc.identifier.urihttps://doi.org/10.1051/0004-6361/201220037
dc.identifier.urihttps://repositorio.uc.cl/handle/11534/101884
dc.identifier.wosidWOS:000310349100031
dc.language.isoen
dc.revistaAstronomy & astrophysics
dc.rightsacceso restringido
dc.subjectstars: horizontal-branch
dc.subjectgalaxies: star clusters: general
dc.subjectglobular clusters: general
dc.subjectultraviolet: stars
dc.subjectgalaxies: stellar content
dc.titleThe horizontal branch morphology of M 31 globular clusters Extreme second parameter effect in outer halo clusters
dc.typeartículo
dc.volumen546
sipa.indexWOS
sipa.trazabilidadWOS;2025-01-12
Files
Collections
Artículos de revistas