Title: VLT/UVES spectroscopy of the O supergiant companion to 4U 1907+09(7)
Authors: Cox, Nicky ×
Kaper, L
Mokiem, MR #
Issue Date: Jun-2005
Publisher: Springer-Verlag
Series Title: Astronomy & Astrophysics vol:436 issue:2 pages:661-669
Abstract: High-resolution optical spectra of the high-mass X-ray binary 4U 1907+09 covering the wavelength range 4680-10400 A indicate that the X-ray pulsar's massive companion is an O8/O9 supergiant with a dense stellar wind. The interstellar atomic lines of Na I and K I of this strongly reddened source (E(B-V) = 3.45 mag) are used to set a lower limit to its distance: d approximate to 5 kpc, excluding the possibility that the massive companion is a Be star. We re-evaluate the system parameters; the new spectral classification of 4U 1907+ 09's O supergiant companion is discussed in the context of its similarity in X-ray and orbital properties to Wray 15-977/GX 301-2. The Ha line shows variability similar to what is observed in other wind-fed systems. A remarkable feature is the strong He II 4686 A emission line, which possibly originates in the accretion flow towards the X-ray pulsar.
ISSN: 0004-6361
Publication status: published
KU Leuven publication type: IT
Appears in Collections:Non-KU Leuven Association publications
× corresponding author
# (joint) last author

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