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Heavy Element Abundances in Late-B and Early-A Stars. I. Co-Added IUE Spectra of HgMn Stars

Adelman, S J; Proffitt, C R; Wahlgren, Glenn LU ; Leckrone, D S and Dolk, Linus LU (2004) In The Astrophysical Journal Supplement Series 155(1). p.179-189
Abstract
Very heavy elements (Pt, Au, Hg, Tl, and Bi) are found to be enhanced inthe atmospheres of the chemically peculiar stars of the upper mainsequence by up to a million times the solar system levels. Suchenhancements are believed to result from atmospheric dynamics (i.e.,diffusion) rather than scenarios that dredge up nuclear-processedmaterial to the surface or transfer processed material between binarycompanions. However, the theoretical framework needs to be furtherconstrained by observations beyond the realm of the spectral types forwhich such abundance enhancements are observed at optical wavelengths.The International Ultraviolet Explorer (IUE) satellite collected spectraof bright stars for which chemical peculiarities have been derived... (More)
Very heavy elements (Pt, Au, Hg, Tl, and Bi) are found to be enhanced inthe atmospheres of the chemically peculiar stars of the upper mainsequence by up to a million times the solar system levels. Suchenhancements are believed to result from atmospheric dynamics (i.e.,diffusion) rather than scenarios that dredge up nuclear-processedmaterial to the surface or transfer processed material between binarycompanions. However, the theoretical framework needs to be furtherconstrained by observations beyond the realm of the spectral types forwhich such abundance enhancements are observed at optical wavelengths.The International Ultraviolet Explorer (IUE) satellite collected spectraof bright stars for which chemical peculiarities have been derived fromground-based data. For several elements the abundance enhancements haveonly been recently measured using Hubble Space Telescope data and havetherefore not yet been exploited in the IUE data. We have initiated aprogram to analyze IUE high-dispersion spectra to more fullycharacterize the pattern of very heavy element enhancement for manymercury-manganese (HgMn) stars and to potentially extend the spectralclass (effective temperature) boundaries over which these abundanceanomalies are known to exist. The abundances of very heavy elements inchemically normal B and A-type stars provide a base level that may becompared with the solar system abundances. These early spectral typestars may therefore reveal clues for galactic chemical evolution studiessince they were formed at a later epoch than the Sun in the history ofthe Galaxy. This first paper presents the motivation for the analyses tofollow, outlines our spectral co-addition technique for IUE spectra, anddiscusses the choice of model atmospheres and the synthetic spectrumprocedures, while initiating the study by highlighting the abundance ofgold in several HgMn stars. (Less)
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author
organization
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Contribution to journal
publication status
published
subject
keywords
Ultraviolet: Stars, Stars: Abundances, Stars: Chemically Peculiar
in
The Astrophysical Journal Supplement Series
volume
155
issue
1
pages
179 - 189
publisher
University of Chicago Press
external identifiers
  • wos:000224700400012
  • scopus:10044267833
ISSN
0067-0049
DOI
10.1086/424802
language
English
LU publication?
yes
id
f2108fad-958d-4aa1-bc5b-d6bc1f3c1293 (old id 134078)
date added to LUP
2007-07-12 13:38:21
date last changed
2017-09-17 07:02:08
@article{f2108fad-958d-4aa1-bc5b-d6bc1f3c1293,
  abstract     = {Very heavy elements (Pt, Au, Hg, Tl, and Bi) are found to be enhanced inthe atmospheres of the chemically peculiar stars of the upper mainsequence by up to a million times the solar system levels. Suchenhancements are believed to result from atmospheric dynamics (i.e.,diffusion) rather than scenarios that dredge up nuclear-processedmaterial to the surface or transfer processed material between binarycompanions. However, the theoretical framework needs to be furtherconstrained by observations beyond the realm of the spectral types forwhich such abundance enhancements are observed at optical wavelengths.The International Ultraviolet Explorer (IUE) satellite collected spectraof bright stars for which chemical peculiarities have been derived fromground-based data. For several elements the abundance enhancements haveonly been recently measured using Hubble Space Telescope data and havetherefore not yet been exploited in the IUE data. We have initiated aprogram to analyze IUE high-dispersion spectra to more fullycharacterize the pattern of very heavy element enhancement for manymercury-manganese (HgMn) stars and to potentially extend the spectralclass (effective temperature) boundaries over which these abundanceanomalies are known to exist. The abundances of very heavy elements inchemically normal B and A-type stars provide a base level that may becompared with the solar system abundances. These early spectral typestars may therefore reveal clues for galactic chemical evolution studiessince they were formed at a later epoch than the Sun in the history ofthe Galaxy. This first paper presents the motivation for the analyses tofollow, outlines our spectral co-addition technique for IUE spectra, anddiscusses the choice of model atmospheres and the synthetic spectrumprocedures, while initiating the study by highlighting the abundance ofgold in several HgMn stars.},
  author       = {Adelman, S J and Proffitt, C R and Wahlgren, Glenn and Leckrone, D S and Dolk, Linus},
  issn         = {0067-0049},
  keyword      = {Ultraviolet: Stars,Stars: Abundances,Stars: Chemically Peculiar},
  language     = {eng},
  number       = {1},
  pages        = {179--189},
  publisher    = {University of Chicago Press},
  series       = {The Astrophysical Journal Supplement Series},
  title        = {Heavy Element Abundances in Late-B and Early-A Stars. I. Co-Added IUE Spectra of HgMn Stars},
  url          = {http://dx.doi.org/10.1086/424802},
  volume       = {155},
  year         = {2004},
}