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A selection of hot subluminous stars in the GALEX survey – II. Subdwarf atmospheric parameters

Authors

  • Péter Németh,

    Corresponding author
    • Astronomický ústav AV ČR, Ondřejov, Czech Republic
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    • Visiting Astronomer, Kitt Peak National Observatory, National Optical Astronomy Observatory, which is operated by the Association of Universities for Research in Astronomy (AURA) under cooperative agreement with the National Science Foundation.

  • Adéla Kawka,

    Corresponding author
    • Astronomický ústav AV ČR, Ondřejov, Czech Republic
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    • Visiting Astronomer, Kitt Peak National Observatory, National Optical Astronomy Observatory, which is operated by the Association of Universities for Research in Astronomy (AURA) under cooperative agreement with the National Science Foundation.

  • Stéphane Vennes

    Corresponding author
    • Astronomický ústav AV ČR, Ondřejov, Czech Republic
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    • Visiting Astronomer, Kitt Peak National Observatory, National Optical Astronomy Observatory, which is operated by the Association of Universities for Research in Astronomy (AURA) under cooperative agreement with the National Science Foundation.


  • Based on observations made with ESO telescopes at the La Silla Paranal Observatory under programmes 82.D-0750, 83.D-0540 and 85.D-0866.

E-mail: pnemeth1981@gmail.com (PN); kawka@sunstel.asu.cas.cz (AK); vennes@sunstel.asu.cas.cz (SV)

ABSTRACT

We present an update of our low-resolution spectroscopic follow-up and model atmosphere analysis of hot subdwarf stars from the Galaxy Evolution Explorer (GALEX) survey. Targets were selected on the basis of colour indices calculated from the GALEX GR6 NUV, Guide Star Catalogue (GSC2.3.2) V and the Two Micron All Sky Survey (2MASS) J and H photometry. High signal-to-noise ratio spectra were obtained at the European Southern Observatory (ESO) and the Kitt Peak National Observatory (KPNO) over the course of three years. Detailed H, He and CNO abundance analysis helped us improve our Teff, log g and He abundance determination and to constrain CNO abundances. We processed 191 observations of 180 targets and found 124 sdB and 42 sdO stars in this sample while some blue horizontal branch stars were also found in this programme. With quantitative binary decomposition of 29 composite spectra we investigated the incidence of A, F and G type companions. The incidence of late G and K type companions and their effects on subdwarf atmospheric parameters were also examined.

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