Hot subdwarf stars in close-up view IV. Helium abundances and the 3He isotopic anomaly of subdwarf B stars

dc.contributor.authorGeier, S.
dc.contributor.authorEdelmann, H.
dc.contributor.authorKilkenny, David
dc.contributor.authorO'Donoghue, D.
dc.contributor.authorMarsh, T.R.
dc.contributor.authorCopperwheat, C.
dc.date.accessioned2017-02-15T10:32:23Z
dc.date.available2017-02-15T10:32:23Z
dc.date.issued2013
dc.description.abstractAtmospheric parameters and helium abundances of 44 bright subdwarf B stars have been determined. More than half of our sample consists of newly discovered stars from the Edinburgh Cape survey. We showed that effective temperatures and surface gravities can be derived from high resolution echelle spectra with sufficient accuracy. Systematic uncertainties have been determined by comparing the parameters derived from the high resolution data with the ones derived from medium resolution spectra. Helium abundances have been measured with high accuracy. Besides the known correlation of helium abundance with temperature, two distinct sequences in helium abundance have been confirmed. Significant isotopic shifts of helium lines due to an enrichment in 3He have been found in the spectra of 8 subluminous B stars (sdBs). Most of these stars cluster in a small temperature range between 27 000K and 31 000K very similar to the known 3He-rich main sequence B stars, which also cluster in such a small strip, but at different temperatures. Both the helium sequences and the isotopic anomaly are discussed.en_US
dc.description.accreditationWeb of Scienceen_US
dc.identifier.citationGeier, S. et al (2013). Hot subdwarf stars in close-up view: IV. Helium abundances and the 3He isotopic anomaly of subdwarf B stars. Astronomy & Astrophysics, 557: A122en_US
dc.identifier.issn0004-6361
dc.identifier.urihttp://hdl.handle.net/10566/2528
dc.identifier.urihttp://dx.doi.org/10.1051/0004-6361/201322057
dc.language.isoen
dc.privacy.showsubmitterFALSE
dc.publisherEDP Sciencesen_US
dc.rightsEDP Open provides free access to enable rapid knowledge transfer and to stimulate further developments and applications.
dc.status.ispeerreviewedFALSE
dc.subjectStarsen_US
dc.subjectAstronomyen_US
dc.subjectAtmospheresen_US
dc.subjectHeliumen_US
dc.subjectSubdwarf starsen_US
dc.titleHot subdwarf stars in close-up view IV. Helium abundances and the 3He isotopic anomaly of subdwarf B stars
dc.typeArticleen_US

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