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dc.contributor.authorKaviraj, S.
dc.contributor.authorSohn, S.T.
dc.contributor.authorO'Connell, R.W.
dc.contributor.authorYoon, S.-J.
dc.contributor.authorLee, Y.W.
dc.contributor.authorYi, S.K.
dc.date.accessioned2013-10-30T10:31:06Z
dc.date.available2013-10-30T10:31:06Z
dc.date.issued2007-05-01
dc.identifier.citationKaviraj , S , Sohn , S T , O'Connell , R W , Yoon , S-J , Lee , Y W & Yi , S K 2007 , ' UV bright globular clusters in M87 : More evidence for super-He-rich stellar populations? ' , Monthly Notices of the Royal Astronomical Society , vol. 377 , no. 3 , pp. 987-996 . https://doi.org/10.1111/j.1365-2966.2007.11712.x
dc.identifier.issn0035-8711
dc.identifier.otherPURE: 2066725
dc.identifier.otherPURE UUID: 951aac0a-4980-464e-a325-4f92fad0a5f1
dc.identifier.otherScopus: 34248158064
dc.identifier.urihttp://hdl.handle.net/2299/11915
dc.description.abstractWe study the ultraviolet (UV) and optical properties of 38 massive globular clusters (GCs) in the Virgo elliptical, M87, imaged using the STIS and WFPC2 instruments onboard the Hubble Space Telescope. The majority of these GCs appear extremely bright in the far-UV (FUV) - roughly a magnitude brighter than their Galactic counterparts with similar metallicities. The observed FUV flux is several times larger than predictions of canonical old stellar population models. These canonical models, which assume a fiducial helium enrichment parameter, are able to reproduce the observed FUV fluxes only if ages ∼3-5 Gyr larger than the Wilkinson Microwave Anisotropy Probe (WMAP) age of the Universe are invoked, although the same models fit the UV photometry of Galactic and M31 GCs for ages less than the 'WMAP age'. A similar discrepancy (∼3 Gyr) is found between the mass-weighted and UV-luminosity-weighted ages of the massive Galactic GC ω Cen, whose colour-magnitude diagram (including peculiar features on its well-populated horizontal branch) can be accurately reproduced by invoking a small super-He-rich stellar component. By comparison to ω Cen, we propose that the majority of M87 GCs in our sample contain strong signatures of similarly minor super-He-rich subcomponents. This hypothesis is supported by simulations which suggest that, based on the UV detection limit of this survey, the number of GCs detected is several times that predicted by canonical models. Although we cannot prove or disprove the extreme helium scenario at the moment, we show that the same phenomenon that causes the extended horizontal branch of ω Cen explains the UV brightness of our sample. If this is indeed due to the extreme helium, this study would be the first to find its signatures in extragalactic objects.en
dc.format.extent10
dc.language.isoeng
dc.relation.ispartofMonthly Notices of the Royal Astronomical Society
dc.rights/dk/atira/pure/core/openaccesspermission/open
dc.titleUV bright globular clusters in M87 : More evidence for super-He-rich stellar populations?en
dc.contributor.institutionSchool of Physics, Astronomy and Mathematics
dc.contributor.institutionScience & Technology Research Institute
dc.contributor.institutionCentre for Astrophysics Research
dc.description.statusPeer reviewed
dc.identifier.urlhttp://www.scopus.com/inward/record.url?scp=34248158064&partnerID=8YFLogxK
dc.relation.schoolSchool of Physics, Astronomy and Mathematics
dc.description.versiontypeSubmitted Version
rioxxterms.versionSMUR
rioxxterms.versionofrecordhttps://doi.org/10.1111/j.1365-2966.2007.11712.x
rioxxterms.typeJournal Article/Review
herts.preservation.rarelyaccessedtrue
herts.rights.accesstyperestrictedAccess


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