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Astron. Astrophys. 321, 776-790 (1997)

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Spectral and timing behaviour of GS 2023+338

T. Oosterbroek 1, M. van der Klis 1, J. van Paradijs 1, 2, B. Vaughan 1, R. Rutledge 3, W.H.G. Lewin 3, Y. Tanaka 4, F. Nagase 4, T. Dotani 4, K. Mitsuda 4 and S. Miyamoto 5

1 Astronomical Institute "Anton Pannekoek", University of Amsterdam, and Center for High Energy Astrophysics, Kruislaan 403, 1098 SJ Amsterdam
2 Physics Department, University of Alabama, Huntsville, AL 35899, USA
3 Massachusetts Institute of Technology, 37-627, Cambridge, MA 02139, USA
4 Institute of Space and Astronautical Science, Yoshinodai 3-1-1, Sagamihara, 229 Kanagawa, Japan
5 Osaka University of Health and Sports Science, Noda 1558-1, Kumatori-cho, Sennan-gun, Osaka 590-04, Japan

Received 11 September 1996 / Accepted 7 October 1996


We have studied the spectral and rapid variations of GS 2023+338 using all Ginga (LAC) data available of this source. We used colour-colour and hardness-intensity diagrams to study the spectral behaviour and for the variability behaviour we used the FFT-technique to obtain power spectra, the energy dependence of the variability and the energy dependence of the phase delays. We find that the spectral behaviour is strongly influenced by changes in the local absorption. These changes also influence the variability at low photon energies and relatively long time scales ([FORMULA] 1 s). The global shape of the power spectra of GS 2023+338 is similar to that of other black hole candidates in the "low" (hard) state, however, small differences are present in the detailed power spectral shape between those sources.

Key words: accretion, accretion disks – X-rays: stars – stars: individual: GS 2023+338

Send offprint requests to: T. Oosterbroek

© European Southern Observatory (ESO) 1997

Online publication: June 30, 1998