2001A&A...375..498V


C.D.S. - SIMBAD4 rel 1.7 - 2020.07.04CEST20:44:49

2001A&A...375..498V - Astronomy and Astrophysics, volume 375, 498-526 (2001/8-4)

Modelling the orbital modulation of ultraviolet resonance lines in high-mass X-ray binaries.

VAN LOON J.T., KAPER L. and HAMMERSCHLAG-HENSBERGE G.

Abstract (from CDS):

The stellar-wind structure in high-mass X-ray binaries (HMXBs) is investigated through modelling of their ultraviolet (UV) resonance lines. For the OB supergiants in two systems, Vela X-1 and 4U 1700-37, high-resolution UV spectra are available; for Cyg X-1, SMC X-1, and LMC X-4 low-resolution spectra are used. In order to account for the non-monotonic velocity structure of the stellar wind, a modified version of the Sobolev Exact Integration (SEI) method by Lamers et al. (1987ApJ...314..726L) is applied. The orbital modulation of the UV resonance lines provides information on the size of the Stroemgren zone surrounding the X-ray source. The amplitude of the observed orbital modulation (known as the Hatchett-McCray effect), however, also depends on the density- and velocity structure of the ambient wind. Model profiles are presented that illustrate the effect on the appearance of the HM effect by varying stellar-wind parameters. The q parameter of Hatchett & McCray (1977ApJ...211..552H), as well as other parameters describing the supergiant's wind structure, are derived for the 5 systems. The X-ray luminosity needed to create the observed size of the Stroemgren zone is consistent with the observed X-ray flux. The derived wind parameters are compared to those determined in single OB supergiants of similar spectral type. Our models naturally explain the observed absence of the HM effect in 4U 1700-37. The orbital modulation in Vela X-1 indicates that besides the Stroemgren zone other structures are present in the stellar wind (such as a photo-ionization wake). The ratio of the wind velocity and the escape velocity is found to be lower in OB supergiants in HMXBs than in single OB supergiants of the same effective temperature.

Abstract Copyright:

Journal keyword(s): line: profiles - binaries: close - circumstellar matter - stars: early-type - stars: mass-loss - ultraviolet: stars

Simbad objects: 6

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Number of rows : 6

N Identifier Otype ICRS (J2000)
RA
ICRS (J2000)
DEC
Mag U Mag B Mag V Mag R Mag I Sp type #ref
1850 - 2020
#notes
1 SK 160 HXB 01 17 05.1447530244 -73 26 36.015353425 12.23 13.00 13.15   13.17 O9.7Ia+ 798 0
2 X LMC X-4 HXB 05 32 49.5558669817 -66 22 13.202534152   13.9 14.0     O8III 609 0
3 X LMC X-1 HXB 05 39 38.8285930597 -69 44 35.533031148   14.8 14.5     O8(f)p 560 2
4 V* GP Vel HXB 09 02 06.8610736194 -40 33 16.896402010 6.85 7.37 6.87 6.31 6.05 B0.5Ia 1373 0
5 HD 153919 HXB 17 03 56.7728262865 -37 50 38.912077679 6.06 6.78 6.51 6.08 5.90 O6Iafcp 756 1
6 HD 226868 HXB 19 58 21.6758193269 +35 12 05.782512305 9.38 9.72 8.91 8.42   O9.7Iabpvar 3923 0

    Equat.    Gal    SGal    Ecl

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2020.07.04-20:44:49

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