Spectroscopic follow-up of ultraviolet-excess objects selected from the UVEX survey
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Author
Verbeek, K.
Groot, P.J.
Scaringi, S.
Nelemans, G.
Napiwotzki, R.
Spikings, B.
Drew, J.E.
Østensen, R.H.
Steeghs, D.
Gänsicke, B.T.
Casares, J.
Corral-Santana, J.M.
Corradi, R.L.M.
Deacon, Niall
Drake, J.J.
González-Solares, E.
Irwin, M.J.
Greimel, R.
Heber, U.
Knigge, C.
Attention
2299/10983
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.