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Title: A possible solution to the Lyman/Balmer line problem in hot DA white dwarfs
Authors: Preval, Simon P.
Barstow, Martin A.
Badnell, N. R.
Holberg, J. B.
Hubeny, I.
First Published: Jun-2015
Publisher: Astronomical Society of the Pacific
Citation: Astronomical Society of the Pacific Conference Series, 2015, Volume 493 : 19th European Workshop on White Dwarfs, 415
Abstract: Arguably, the best method for determining the effective temperature (T[subscript: eff]) and surface gravity (log g) of a DA white dwarf is by fitting the Hydrogen Lyman and Balmer absorption features. However, as has been shown for white dwarfs with T[subscript: eff]>50,000K, the calculated value from the Lyman and Balmer lines are discrepant, which worsens with increasing temperature. Many different solutions have been suggested, ranging from the input physics used to calculate the models, to interstellar reddening. We will focus on the former, and consider three variables. The first is the atomic data used, namely the number of transitions included in line blanketing treatments and the photoionization cross sections. The second is the stark broadening treatment used to synthesise the Lyman and Balmer line profiles, namely the calculations performed by Lemke (1997) and Tremblay & Bergeron (2009). Finally, the third is the atmospheric content. The model grids are calculated with a pure H composition, and a metal polluted composition using the abundances of Preval et al. (2013). We present the preliminary results of our analysis, whereby we have determined the T[subscript: eff] for a small selection of white dwarfs. We plan to extend our analysis by allowing metallicity to vary in future model grids.
ISSN: 1050-3390
Version: Post-print
Status: Peer-reviewed
Type: Journal Article
Rights: Copyright © 2015 Astronomical Society of the Pacific. Deposited with reference to the publisher’s open access archiving policy, available at The file associated with this record is under a 12-month embargo from publication in accordance with the publisher's self-archiving policy.The full text may be available in the publisher links provided above.
Description: 5 pages, 1 figure, 1 table: To appear in the proceedings of the "19th European White Dwarf Workshop" in Montreal, Canada, 2014
Appears in Collections:Published Articles, Dept. of Physics and Astronomy

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