Issue |
A&A
Volume 614, June 2018
|
|
---|---|---|
Article Number | A96 | |
Number of page(s) | 4 | |
Section | Stellar atmospheres | |
DOI | https://doi.org/10.1051/0004-6361/201832723 | |
Published online | 20 June 2018 |
First detection of bromine and antimony in hot stars★,★★
1
Institute for Astronomy and Astrophysics, Kepler Center for Astro and Particle Physics, Eberhard Karls University,
Sand 1,
72076
Tübingen,
Germany
e-mail: werner@astro.uni-tuebingen.de
2
NASA Goddard Space Flight Center,
Greenbelt,
MD
20771,
USA
Received:
29
January
2018
Accepted:
3
March
2018
Bromine (Z = 35) and antimony (Z = 51) are extremely difficult to detect in stars. In very few instances, weak and mostly uncertain identifications of Br I, Br II, and Sb II in relatively cool, chemically peculiar stars were successful. Adopted solar abundance values rely on meteoritic determinations. Here, we announce the first identification of these species in far-ultraviolet spectra of hot stars (with effective temperatures of 49 500–70 000 K), namely in helium-rich (spectral type DO) white dwarfs. We identify the Br VI resonance line at 945.96 Å. A previous claim of Br detection based on this line is incorrect because its wavelength position is inaccurate by about 7 Å in atomic databases. Taking advantage of precise laboratory measurements, we identify this line as well as two other, subordinate Br VI lines. Antimony is detected by the Sb V resonance doublet at 1104.23/1225.98 Å as well as two subordinate Sb VI lines. A model-atmosphere analysis reveals strongly oversolar Br and Sb abundances that are caused by radiative-levitation dominated atomic diffusion.
Key words: diffusion / stars: abundances / stars: atmospheres / stars: AGB and post-AGB / white dwarfs
© ESO 2018
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