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Title: Improved determination of the atmospheric parameters of the pulsating sdB star Feige 48

As part of a multifaceted effort to better exploit the asteroseismological potential of the pulsating sdB star Feige 48, we present an improved spectroscopic analysis of that star based on new grids of NLTE, fully line-blanketed model atmospheres. To that end, we gathered four high signal-to-noise ratio time-averaged optical spectra of varying spectral resolutions from 1.0 Å to 8.7 Å, and we made use of the results of four independent studies to fix the abundances of the most important metals in the atmosphere of Feige 48. The mean atmospheric parameters we obtained from our four spectra of Feige 48 are: T {sub eff} = 29,850 ± 60 K, log g = 5.46 ± 0.01, and log N(He)/N(H) = –2.88 ± 0.02. We also modeled, for the first time, the He II line at 1640 Å from the STIS archive spectrum of the star, and with this line we found an effective temperature and a surface gravity that match well with the values obtained with the optical data. With some fine tuning of the abundances of the metals visible in the optical domain, we were able to achieve a very good agreement between our best available spectrum and our best-fitting syntheticmore » one. Our derived atmospheric parameters for Feige 48 are in rather good agreement with previous estimates based on less sophisticated models. This underlines the relatively small effects of the NLTE approach combined with line blanketing in the atmosphere of this particular star, implying that the current estimates of the atmospheric parameters of Feige 48 are reliable and secure.« less
Authors:
; ;  [1] ;  [2] ;  [3]
  1. Département de Physique, Université de Montréal, Succ. Centre-Ville, C. P. 6128, Montréal, QC H3C 3J7 (Canada)
  2. Steward Observatory, University of Arizona, 933 North Cherry Avenue, Tucson, AZ 85721 (United States)
  3. Space Telescope Science Institute, 3700 San Martin Drive, Baltimore, MD 21218 (United States)
Publication Date:
OSTI Identifier:
22356653
Resource Type:
Journal Article
Resource Relation:
Journal Name: Astrophysical Journal; Journal Volume: 788; Journal Issue: 1; Other Information: Country of input: International Atomic Energy Agency (IAEA)
Country of Publication:
United States
Language:
English
Subject:
79 ASTROPHYSICS, COSMOLOGY AND ASTRONOMY; ABUNDANCE; ATMOSPHERES; GRAVITATION; METALS; RESOLUTION; SIGNAL-TO-NOISE RATIO; SPECTRA; STARS; SURFACES