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Hot subdwarf stars in close-up view
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Geier, S., Heber, U., Edelmann, H., Morales-Rueda, L., Kilkenny, D., O’Donoghue, D., Marsh, Tom and Copperwheat, C. M. (2013) Hot subdwarf stars in close-up view. Astronomy & Astrophysics, Volume 557 . A122. doi:10.1051/0004-6361/201322057 ISSN 0004-6361.
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Official URL: http://dx.doi.org/10.1051/0004-6361/201322057
Abstract
Atmospheric 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 27 000 K and 31 000 K 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.
Item Type: | Journal Article | ||||||
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Divisions: | Faculty of Science, Engineering and Medicine > Science > Physics | ||||||
Journal or Publication Title: | Astronomy & Astrophysics | ||||||
Publisher: | EDP Sciences | ||||||
ISSN: | 0004-6361 | ||||||
Official Date: | September 2013 | ||||||
Dates: |
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Volume: | Volume 557 | ||||||
Article Number: | A122 | ||||||
DOI: | 10.1051/0004-6361/201322057 | ||||||
Status: | Peer Reviewed | ||||||
Publication Status: | Published | ||||||
Access rights to Published version: | Restricted or Subscription Access |
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