Physical parameters of helium-rich subdwarf B stars 
 from spectral energy distributions

Ahmad, Amir; Jeffery, C. S.

doi:10.1051/0004-6361:20031577

Cited by 5 publications

(1 citation statement)

References 25 publications

(18 reference statements)

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“…This builds on earlier efforts to determine the physical parameters of He-sdBs using optical spectroscopy (e.g. Ahmad & Jeffery 2003;Ahmad & Jeffery 2004). By collecting this information, it becomes possible to search for patterns within the He-sdB class and to identify possible connections with other classes of evolved stars.…”

Section: Introductionmentioning

confidence: 99%

Spectroscopic analysis of BPS CS 22940−0009: connecting evolved helium stars

Snowdon

Scott

Jeffery

et al. 2022

Monthly Notices of the Royal Astronomical Society

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BPS CS 22940−0009 is a helium-rich B-star that shares characteristics with both helium-rich B subdwarfs and extreme helium stars. The optical spectrum of BPS CS 22940−0009 has been analysed from SALT observations. The atmospheric parameters were found to be Teff = 34 970 ± 370 K, log g/cm s−2 = 4.79 ± 0.17, nH/nHe ≃ 0.007, nC/nHe ≃ 0.007, nN/nHe ≃ 0.002, although further improvement to the helium line fits would be desirable. This places the star as a link between the He-sdB and EHe populations in g-T space. The abundance profile shows enrichment of N from CNO-processing, and C from 3α burning. Depletion of Al, Si, S and a low upper limit for Fe show the star to be intrinsically metal-poor. The results are consistent with BPS CS 22940−0009 having formed from the merger of two helium white dwarfs and currently evolving toward the helium main sequence.

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Section: Introductionmentioning

confidence: 99%

Spectroscopic analysis of BPS CS 22940−0009: connecting evolved helium stars

Snowdon

Scott

Jeffery

et al. 2022

Monthly Notices of the Royal Astronomical Society

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Stellar Structure and Evolution: An Introduction

Jeffery

2010

Astrophysics and Space Science Proceedings

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Discovery of a spectroscopic binary comprising two hot helium-rich subdwarfs

Ahmad

Jeffery

Fullerton

2004

A&A

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Abstract. Helium-rich subdwarf B (He-sdB) stars form a very small fraction of the population of hot subdwarf stars in our Galaxy. They have been found both in the field of our Galaxy as well as in globular clusters. The evolution of these rare stars has recently been the subject of much debate involving both binary and single star evolution models. We report our serendipitous discovery that the prototype -PG 1544+488 -is a binary containing two low-mass helium-rich hot subdwarfs. This discovery challenges existing evolutionary models for He-sdB stars and suggests that they may be formed through close binary evolution and following the ejection of a common envelope.

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Physical parameters of helium-rich subdwarf B stars from spectral energy distributions

Cited by 5 publications

References 25 publications

Spectroscopic analysis of BPS CS 22940−0009: connecting evolved helium stars

Spectroscopic analysis of BPS CS 22940−0009: connecting evolved helium stars

Stellar Structure and Evolution: An Introduction

Discovery of a spectroscopic binary comprising two hot helium-rich subdwarfs

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