Observations of Cygnus X-2 with IUE : ultraviolet results from a multiwavelength campaign.
Abstract
IUE observations of Cyg X-2 obtained during June and October 1988 are reported and analyzed, with reference to data from simultaneous X-ray and radio observations and the predictions of theoretical models. The results are presented in extensive tables and graphs and characterized in detail. The UV flux is shown to increase monotonically as the X-ray emission moves along the Z-shaped trajectory from the horizontal to the flaring branch and the estimated mass accretion rate increases from about 6 x 10 to the -9th to 1.6 x 10 to the -8th solar mass/yr. Model calculations indicate that X-ray illumination of the accretion disk accounts for at least 80 percent of the observed UV emission, with 20 percent or less from the X-ray-heated surface of the companion star and less than 1 percent from the cool surface.
- Publication:
-
Astronomy and Astrophysics
- Pub Date:
- August 1990
- Bibcode:
- 1990A&A...235..162V
- Keywords:
-
- Neutron Stars;
- Ultraviolet Astronomy;
- Ultraviolet Spectra;
- X Ray Binaries;
- Cygnus Constellation;
- Emission Spectra;
- Iue;
- Stellar Composition;
- Stellar Models;
- Stellar Spectra;
- Astrophysics