Fundamental parameters of He-weak and He-strong stars
نویسندگان
چکیده
منابع مشابه
O(he) Stars
Spectral analyses of H-deficient post-AGB stars have shown that a small group of four extremely hot objects exists which have almost pure He absorption-line spectra in the optical. These are classified as O(He) stars. For their evolution there are two scenarios: They could be the long-sought hot successors of RCrB stars, which have not been identified up to now. If this turns out to be true, th...
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He-weak and He-strong stars are chemically peculiar AB objects whose He lines are anomalously weak or strong for their MK spectral type. The determination of fundamental parameters for these stars is often more complex than for normal stars due to their abundance anomalies. We discuss the determination of fundamental parameters: effective temperature, surface gravity, and visual and bolometric ...
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We present a model of He relaxation on the surface of borosilicate glass which accurately predicts observed relaxation rates and their temperature dependence. Above room temperature He dissolves into Pyrex, where interactions with Fe3þ ions result in a relaxation time of 1 ms. Gas exchange across the glass surface of an enclosed vessel leads to T 1 1 1⁄4 A=V ð3:9 1:4Þ 10 2 cm/h at room temperat...
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ژورنال
عنوان ژورنال: Astronomy & Astrophysics
سال: 2007
ISSN: 0004-6361,1432-0746
DOI: 10.1051/0004-6361:20066454