On possible photometric manifestation of magnetic field in CygX-1

We consider the influence of the magnetic field of the O9.7Iab supergiant component in the CygX-1 X-ray binary system on its atmosphere. In the frame of the simplest model (the unipolar cylindrically symmetric circum-polar magnetic spot model in static approximation, neglecting the Lorentz force com...

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Bibliographic Details
Published in:Advances in space research 2015-02, Vol.55 (3), p.857-861
Main Authors: Karitskaya, E.A., Bochkarev, N.G.
Format: Article
Language:English
Subjects:
Bright spots
Curvature
Cyg X-1
Lorentz force
Magnetic field
Magnetic fields
Magnetic poles
Mathematical analysis
O-supergiant
Photometry
Spots
Star
Stellar spots
X-ray stars
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Summary:We consider the influence of the magnetic field of the O9.7Iab supergiant component in the CygX-1 X-ray binary system on its atmosphere. In the frame of the simplest model (the unipolar cylindrically symmetric circum-polar magnetic spot model in static approximation, neglecting the Lorentz force component related to the force line curvature), the magnetic pressure is found to be comparable to model-atmosphere gas and radiative pressure, exceeding them in the area around the magnetic poles. As a result, bright spots are formed on the star surface. The dipolar or quadrupolar magnetic field can create large-size bright spots which can be studied by ground-based optical photometry. In the case of magnetic field inclined to the stellar rotation axis, resulting variability may be of the order of 1%. The field of higher multipolar configuration (produced by dynamo) can form smaller spots and may be detected only by space telescopes. Besides, the spots may be revealed from spectral-line profile variability. Observations of spots can be used as an instrument of magnetic field analysis.
ISSN:0273-1177
1879-1948
DOI:10.1016/j.asr.2014.06.026