Published by
EDP Sciences
EDP Sciences Journals List
Subscriber Authentication Point
Home All issues Volume 402/ 1 Article
Free access
Issue A&A
Volume 402, Number 1, April IV 2003
Page(s) 237 - 246
Section Stellar atmospheres
DOI http://dx.doi.org/10.1051/0004-6361:20030148



A&A 402, 237-246 (2003)
DOI: 10.1051/0004-6361:20030148

Variability of the H $\alpha$ emission of Cygnus X-1 and its connection with the soft X-ray radiation

A. E. Tarasov1, C. Brocksopp2 and V. M. Lyuty3

1  Crimean Astrophysical Observatory and Isaac Newton Institute of Chile, Crimean branch, 98409 Nauchny, Crimea, Ukraine
2  Astrophysics Research Institute, Liverpool John Moores University, Twelve Quays House, Egerton Wharf, Birkenhead CH41 1LD, UK
3  Sternberg Astronomical Institute, Universitetskii pr. 13, Moscow, 119899 Russia

(Received 9 July 2002 / Accepted 28 January 2003 )

Abstract
High-resolution H $\alpha$ monitoring of Cyg X-1, HD 226868 was carried out during 1996-2002 and the resultant spectra analysed in conjunction with 1.5-12 keV X-ray monitoring. We demonstrate that the H $\alpha$ line-profiles have complex variability on different timescales, controlled in particular by the orbital period and the focused wind model of mass loss. We find that long-term variability of the mass loss by the supergiant and short-term variability due to clumpy structure of the stellar wind dominate during the low/hard X-ray state and that X-ray photoionization has a relatively small influence on the line-profile shape and EW variability. During the high/soft X-ray state and flaring the effect of photoionization the line-profile and EW of H $\alpha$ increases but is still unable to describe the loose anti-correlation between EW and the low energy X-ray emission. We propose that variability of the mass loss by the supergiant can change wind velocities in the Strömgren zone around the accretion disc of the secondary, leading to an increase in accretion rate through the disc.


Key words: binaries: spectroscopic -- stars: early-type -- stars: winds, outflows -- stars: individual: HD 226868, Cyg X-1 -- X-rays: binaries

Offprint request: A. E. Tarasov, tarasov@crao.crimea.ua

SIMBAD Objects



© ESO 2003

What is OpenURL?

The OpenURL standard is a protocol for transmission of metadata describing the resource that you wish to access. An OpenURL link contains article metadata and directs it to the OpenURL server of your choice. The OpenURL server can provide access to the resource and also offer complementary services (specific search engine, export of references...). The OpenURL link can be generated by different means.
  • If your librarian has set up your subscription with an OpenURL resolver, OpenURL links appear automatically on the abstract pages.
  • You can define your own OpenURL resolver with your EDPS Account. In this case your choice will be given priority over that of your library.
  • You can use an add-on for your browser (Firefox or I.E.) to display OpenURL links on a page (see http://www.openly.com/openurlref/). You should disable this module if you wish to use the OpenURL server that you or your library have defined.