| Autor: |
Snowdon, E J, Scott, L J A, Jeffery, C S, Woolf, V M |
| Předmět: |
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| Zdroj: |
Monthly Notices of the Royal Astronomical Society; 10/15/2022, Vol. 516 Issue 1, p794-810, 17p |
| Abstrakt: |
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 |$T_{\rm eff} = 34\, 970 \pm 370$| K, |$\log g/{\rm cm\, s^{-2}} = 4.79 \pm 0.17$| , n H/ n He ≃ 0.007, n C/ n He ≃ 0.007, n N/ n He ≃ 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 towards the helium main sequence. [ABSTRACT FROM AUTHOR] |
| Databáze: |
Complementary Index |
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