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On the Ga II and Ga III resonance lines and the implication for chemical stratification in HGMN stars

Nielsen, Krister LU ; Wahlgren, Glenn LU ; Proffitt, CR; Leckrone, DS and Adelman, SJ (2005) In Astronomical Journal 130(5). p.2312-2317
Abstract
The gallium abundance in HgMn stars has been reported to be different for analyses conducted from spectral lines in the optical versus those from the ultraviolet. We pursue this ultraviolet-optical discrepancy from a line-blending perspective by investigating the Hubble Space Telescope (HST) Space Telescope Imaging Spectrograph (STIS) spectrum of the sharp-lined HgMn binary star chi Lup. Its gallium abundance is derived to be log N-Ga = 4.5 (log N-H = 12) based on nonresonance Ga II lines, and we are able to demonstrate the line-blending problems associated with the abundances determined from the resonance lines of Ga II lambda 1414 and Ga III lambda 1495. The HST STIS spectrum for chi Lup is also compared with a co-added International... (More)
The gallium abundance in HgMn stars has been reported to be different for analyses conducted from spectral lines in the optical versus those from the ultraviolet. We pursue this ultraviolet-optical discrepancy from a line-blending perspective by investigating the Hubble Space Telescope (HST) Space Telescope Imaging Spectrograph (STIS) spectrum of the sharp-lined HgMn binary star chi Lup. Its gallium abundance is derived to be log N-Ga = 4.5 (log N-H = 12) based on nonresonance Ga II lines, and we are able to demonstrate the line-blending problems associated with the abundances determined from the resonance lines of Ga II lambda 1414 and Ga III lambda 1495. The HST STIS spectrum for chi Lup is also compared with a co-added International Ultraviolet Explorer (IUE) spectrum to further illustrate the importance of accounting for the line blending in quantitative abundance analyses. We have compared an IUE co-added spectrum of mu Lep with an LTE-based synthetic spectrum and managed to fit both Ga II lambda 1414 and Ga III lambda 1495 with an abundance of log N-Ga = 7.3. However, the fitting of these lines requires a dramatic change in the radiative damping constants, which may indicate a breakdown in our LTE modeling or the need to include other atmospheric effects. (Less)
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author
organization
publishing date
type
Contribution to journal
publication status
published
subject
keywords
stars : abundances, stars : chemically peculiar, ultraviolet : stars, line : profiles
in
Astronomical Journal
volume
130
issue
5
pages
2312 - 2317
publisher
The American Astronomical Society
external identifiers
  • wos:000232977900030
  • scopus:28944436234
ISSN
1538-3881
DOI
10.1086/491703
language
English
LU publication?
yes
id
ca6aa3c1-044c-468e-a3c4-9a939a6b1cbf (old id 214322)
date added to LUP
2007-08-21 08:52:51
date last changed
2017-06-11 03:55:40
@article{ca6aa3c1-044c-468e-a3c4-9a939a6b1cbf,
  abstract     = {The gallium abundance in HgMn stars has been reported to be different for analyses conducted from spectral lines in the optical versus those from the ultraviolet. We pursue this ultraviolet-optical discrepancy from a line-blending perspective by investigating the Hubble Space Telescope (HST) Space Telescope Imaging Spectrograph (STIS) spectrum of the sharp-lined HgMn binary star chi Lup. Its gallium abundance is derived to be log N-Ga = 4.5 (log N-H = 12) based on nonresonance Ga II lines, and we are able to demonstrate the line-blending problems associated with the abundances determined from the resonance lines of Ga II lambda 1414 and Ga III lambda 1495. The HST STIS spectrum for chi Lup is also compared with a co-added International Ultraviolet Explorer (IUE) spectrum to further illustrate the importance of accounting for the line blending in quantitative abundance analyses. We have compared an IUE co-added spectrum of mu Lep with an LTE-based synthetic spectrum and managed to fit both Ga II lambda 1414 and Ga III lambda 1495 with an abundance of log N-Ga = 7.3. However, the fitting of these lines requires a dramatic change in the radiative damping constants, which may indicate a breakdown in our LTE modeling or the need to include other atmospheric effects.},
  author       = {Nielsen, Krister and Wahlgren, Glenn and Proffitt, CR and Leckrone, DS and Adelman, SJ},
  issn         = {1538-3881},
  keyword      = {stars : abundances,stars : chemically peculiar,ultraviolet : stars,line : profiles},
  language     = {eng},
  number       = {5},
  pages        = {2312--2317},
  publisher    = {The American Astronomical Society},
  series       = {Astronomical Journal},
  title        = {On the Ga II and Ga III resonance lines and the implication for chemical stratification in HGMN stars},
  url          = {http://dx.doi.org/10.1086/491703},
  volume       = {130},
  year         = {2005},
}