Hot subdwarf stars in close-up view: IV. Helium abundances and the 3he isotopic anomaly of subdwarf b stars
Geier S, Heber U, Edelmann H, Morales-Rueda L, Kilkenny D, O'Donoghue D, Marsh TR, Copperwheat C (2013)
Publication Type: Journal article
Publication year: 2013
Journal
Book Volume: 557
Article Number: A122
DOI: 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. © 2013 ESO.
Authors with CRIS profile
Stephan Geier
Dr.Karl-Remeis-Sternwarte Bamberg, Astronomisches Institut
Ulrich Heber
Naturwissenschaftliche Fakultät
Heinz Edelmann
Dr.Karl-Remeis-Sternwarte Bamberg, Astronomisches Institut
Involved external institutions
South African Astronomical Observatory (SAAO)
South Africa (ZA)
Radboud University Nijmegen
Netherlands (NL)
University of the Western Cape (UWC)
South Africa (ZA)
University of Warwick
United Kingdom (GB)
South Africa (ZA)
Radboud University Nijmegen
Netherlands (NL)
University of the Western Cape (UWC)
South Africa (ZA)
University of Warwick
United Kingdom (GB)
How to cite
APA:
Geier, S., Heber, U., Edelmann, H., Morales-Rueda, L., Kilkenny, D., O'Donoghue, D.,... Copperwheat, C. (2013). Hot subdwarf stars in close-up view: IV. Helium abundances and the 3he isotopic anomaly of subdwarf b stars. Astronomy & Astrophysics, 557. https://doi.org/10.1051/0004-6361/201322057
MLA:
Geier, Stephan, et al. "Hot subdwarf stars in close-up view: IV. Helium abundances and the 3he isotopic anomaly of subdwarf b stars." Astronomy & Astrophysics 557 (2013).
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