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Mercury in the HgMn stars chi Lupi and HR 7775

Proffitt, CR; Brage, Tomas LU ; Leckrone, DS; Wahlgren, Glenn LU ; Brandt, JC; Sansonetti, CJ; Reader, J and Johansson, Sveneric LU (1999) In Astrophysical Journal 512(2). p.942-960
Abstract
Observations of mercury lines in the HgMn stars chi Lupi and HR 7775 made with the Hubble Space Telescope Goddard High Resolution Spectrograph are presented and analyzed. In chi Lupi we find that all observed lines are consistent with the same isotopic mixture (essentially pure (204)Hg). Strong ionization anomalies are present, with UV Hg I lines being too weak and Hg III lines too strong for the abundance derived from lines of the majority ionization state, Hg rr. Observations of mercury in I;IR 7775 show less extreme isotope and ionization anomalies. We find that the ionization anomaly in the Hg I resonance lines can be plausibly explained as a non-LTE effect, but the same non-LTE calculations show that the Hg III ionization anomaly in... (More)
Observations of mercury lines in the HgMn stars chi Lupi and HR 7775 made with the Hubble Space Telescope Goddard High Resolution Spectrograph are presented and analyzed. In chi Lupi we find that all observed lines are consistent with the same isotopic mixture (essentially pure (204)Hg). Strong ionization anomalies are present, with UV Hg I lines being too weak and Hg III lines too strong for the abundance derived from lines of the majority ionization state, Hg rr. Observations of mercury in I;IR 7775 show less extreme isotope and ionization anomalies. We find that the ionization anomaly in the Hg I resonance lines can be plausibly explained as a non-LTE effect, but the same non-LTE calculations show that the Hg III ionization anomaly in chi Lupi cannot be explained in this way. Radiative force calculations show that the observed mercury abundance cannot be supported in the atmosphere by the radiative forces alone. We suggest that weak mixing brings mercury into the line-forming region from below the photosphere, while a wind of order 10(-14) M. yr(-1) supports a cloud of Hg III at very small optical depths. (Less)
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author
organization
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Contribution to journal
publication status
published
subject
keywords
HR 7775), stars : peculiar, stars : individual (chi Lupi, diffusion, stars : abundances
in
Astrophysical Journal
volume
512
issue
2
pages
942 - 960
publisher
University of Chicago Press
external identifiers
  • wos:000079809000036
ISSN
0004-637X
DOI
10.1086/306783
language
English
LU publication?
yes
id
975579f1-35a9-4860-80d8-51a03e55a9e0 (old id 3919505)
date added to LUP
2013-07-09 08:10:42
date last changed
2016-04-16 03:29:55
@article{975579f1-35a9-4860-80d8-51a03e55a9e0,
  abstract     = {Observations of mercury lines in the HgMn stars chi Lupi and HR 7775 made with the Hubble Space Telescope Goddard High Resolution Spectrograph are presented and analyzed. In chi Lupi we find that all observed lines are consistent with the same isotopic mixture (essentially pure (204)Hg). Strong ionization anomalies are present, with UV Hg I lines being too weak and Hg III lines too strong for the abundance derived from lines of the majority ionization state, Hg rr. Observations of mercury in I;IR 7775 show less extreme isotope and ionization anomalies. We find that the ionization anomaly in the Hg I resonance lines can be plausibly explained as a non-LTE effect, but the same non-LTE calculations show that the Hg III ionization anomaly in chi Lupi cannot be explained in this way. Radiative force calculations show that the observed mercury abundance cannot be supported in the atmosphere by the radiative forces alone. We suggest that weak mixing brings mercury into the line-forming region from below the photosphere, while a wind of order 10(-14) M. yr(-1) supports a cloud of Hg III at very small optical depths.},
  author       = {Proffitt, CR and Brage, Tomas and Leckrone, DS and Wahlgren, Glenn and Brandt, JC and Sansonetti, CJ and Reader, J and Johansson, Sveneric},
  issn         = {0004-637X},
  keyword      = {HR 7775),stars : peculiar,stars : individual (chi Lupi,diffusion,stars : abundances},
  language     = {eng},
  number       = {2},
  pages        = {942--960},
  publisher    = {University of Chicago Press},
  series       = {Astrophysical Journal},
  title        = {Mercury in the HgMn stars chi Lupi and HR 7775},
  url          = {http://dx.doi.org/10.1086/306783},
  volume       = {512},
  year         = {1999},
}