TY  - JOUR
A1  - Oskinova, Lida
A1  - Feldmeier, Achim
A1  - Kretschmar, Peter
T1  - Clumped stellar winds in supergiant high-mass X-ray binaries: X-ray variability and photoionization
JF  - Monthly notices of the Royal Astronomical Society
N2  - The clumping of massive star winds is an established paradigm, which is confirmed by multiple lines of evidence and is supported by stellar wind theory. The purpose of this paper is to bridge the gap between detailed models of inhomogeneous stellar winds in single stars and the phenomenological description of donor winds in supergiant high-mass X-ray binaries (HMXBs). We use the results from time-dependent hydrodynamical models of the instability in the line-driven wind of a massive supergiant star to derive the time-dependent accretion rate on to a compact object in the BondiHoyleLyttleton approximation. The strong density and velocity fluctuations in the wind result in strong variability of the synthetic X-ray light curves. The model predicts a large-scale X-ray variability, up to eight orders of magnitude, on relatively short time-scales. The apparent lack of evidence for such strong variability in the observed HMXBs indicates that the details of the accretion process act to reduce the variability resulting from the stellar wind velocity and density jumps.
KW  - accretion, accretion discs
KW  - instabilities
KW  - stars: neutron
KW  - X-rays: binaries
KW  - X-rays: stars
Y1  - 2012
U6  - https://doi.org/10.1111/j.1365-2966.2012.20507.x
SN  - 0035-8711
VL  - 421
IS  - 4
SP  - 2820
EP  - 2831
PB  - Wiley-Blackwell
CY  - Malden
ER  -