Astronomy and Astrophysics – Astronomy
Scientific paper
Mar 2000
adsabs.harvard.edu/cgi-bin/nph-data_query?bibcode=2000pasp..112..354s&link_type=abstract
The Publications of the Astronomical Society of the Pacific, Volume 112, Issue 769, pp. 354-358.
Astronomy and Astrophysics
Astronomy
5
Stars: Subdwarfs, Stars: White Dwarfs
Scientific paper
We report the discovery of a peculiar new hot high-gravity predegenerate star, EC 11481-2303 from the Edinburgh-Cape Blue Object Survey, based upon the analysis of far-UV International Ultraviolet Explorer (IUE) echelle and low-resolution spectra and an optical spectrum. The IUE spectra reveal the presence of far-UV photospheric/circumstellar high-ionization absorption features due to N V λλ1238, 1242, Si IV λλ1393, 1402, C IV λλ1548, 1550, and He II λ1640. The mean velocity of these features is -17.5 km s-1. In addition, there is low-ionization interstellar absorption at an average velocity of -5.6 km s-1. The interstellar lines are strong and imply a distance of more than 500 pc. The optical spectrum is dominated by Stark-broadened Balmer absorption, a sharp He II λ4686 feature, and the absence of Balmer members higher than H8. A best-fit model atmosphere to the optical data yields Teff=41,790 K and logg=5.84, suggesting an extended horizontal branch sdOB subdwarf. However, synthetic spectral fits to the far-UV spectrum do not provide a consistent fit to both the Lyα region and the far-UV continuum of EC 11481-2303. It is possible that EC 11481-2303 is an unresolved binary. Follow-up ground-based and far-UV studies are encouraged to discern the possible nature of any binary companion.
Holberg Jay Brian
Kilkenny Dave
Koen Chris
O'Donoghue Darragh
Saffer Rex
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