University of Hertfordshire

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  • 904936

    Submitted manuscript, 3 MB, PDF document

  • K. Verbeek
  • P.J. Groot
  • S. Scaringi
  • G. Nelemans
  • R. Napiwotzki
  • B. Spikings
  • J.E. Drew
  • R.H. Østensen
  • D. Steeghs
  • B.T. Gänsicke
  • J. Casares
  • J.M. Corral-Santana
  • R.L.M. Corradi
  • Niall Deacon
  • J.J. Drake
  • E. González-Solares
  • M.J. Irwin
  • R. Greimel
  • U. Heber
  • C. Knigge
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Original languageEnglish
Number of pages27
Pages (from-to)1235-1261
JournalMonthly Notices of the Royal Astronomical Society
Journal publication date21 Oct 2012
Volume426
Issue2
DOIs
Publication statusPublished - 21 Oct 2012

Abstract

We present the results of the first spectroscopic follow-up of 132 optically blue ultraviolet (UV)-excess sources selected from the UV-Excess Survey of the Northern Galactic Plane (UVEX). The UV-excess spectra are classified into different populations and grids of model spectra are fitted to determine spectral types, temperatures, surface gravities and reddening. From this initial spectroscopic follow-up 95 per cent of the UV-excess candidates turn out to be genuine UV-excess sources such as white dwarfs, white dwarf binaries, subdwarf types O and B, emission-line stars and quasi stellar objects. The remaining sources are classified as slightly reddened main-sequence stars with spectral types later than A0V. The fraction of DA white dwarfs is 47 per cent with reddening smaller than E(B - V) ≤ 0.7mag. Relations between the different populations and their UVEX photometry, Galactic latitude and reddening are shown. A larger fraction of UVEX white dwarfs is found at magnitudes fainter than g > 17 and Galactic latitude smaller than |b| <4 compared to main-sequence stars, blue horizontal branch stars and subdwarfs.

ID: 1950887