First detection of bromine and antimony in hot stars
Abstract
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.
Based on observations made with the NASA-CNES-CSA Far Ultraviolet Spectroscopic Explorer.Based on observations with the NASA/ESA Hubble Space Telescope, obtained at the Space Telescope Science Institute, which is operated by the Association of Universities for Research in Astronomy, Inc., under NASA contract NAS5-26666.- Publication:
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Astronomy and Astrophysics
- Pub Date:
- June 2018
- DOI:
- 10.1051/0004-6361/201832723
- arXiv:
- arXiv:1803.04809
- Bibcode:
- 2018A&A...614A..96W
- Keywords:
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- diffusion;
- stars: abundances;
- stars: atmospheres;
- stars: AGB and post-AGB;
- white dwarfs;
- Astrophysics - Solar and Stellar Astrophysics
- E-Print:
- Accepted for publication in A&