Multifrequency observations of Cygnus X-2 : X-ray observations with Ginga.
Abstract
X-ray observations of Cyg X-2, obtained with the Ginga satellite on 6 days in June and October 1988, are reported and analyzed with reference to data from simultaneous UV and radio observations. The instrumentation and data-reduction procedures are described, and the results are presented in extensive tables and graphs and characterized in detail. The horizontal, normal, and flaring branches of the Z-shaped correlation curve in the X-ray color-color diagram are all observed over a period of about 2 days, with (1) a faint extension of the 55-Hz quasi-periodic oscillation (QPO) into the upper normal branch, (2) a significant increase in the frequency of the 5-Hz QPO down the normal branch and into the lower flaring branch, and (3) a twofold increase in the X-ray and UV flux from the horizontal to the flaring branch (indicating an increase in the accretion rate).
- Publication:
-
Astronomy and Astrophysics
- Pub Date:
- August 1990
- Bibcode:
- 1990A&A...235..131H
- Keywords:
-
- Astronomical Spectroscopy;
- Ginga Satellite;
- Neutron Stars;
- Stellar Mass Accretion;
- X Ray Binaries;
- Cygnus Constellation;
- Japanese Spacecraft;
- Spaceborne Astronomy;
- Stellar Oscillations;
- X Ray Spectra;
- Astrophysics