The quasi-coherent oscillations of SS Cygni
Properties of the quasi-coherent oscillations in the extreme ultraviolet flux of the dwarf nova SS Cygni are described. Rapid periodic oscillations are observed in the optical and soft X-ray flux of high accretion rate cataclysmic variables (CVs; nova-like variables and dwarf novae in outburst). These so-called `dwarf nova oscillations` (DNOS) have high coherence (Q {approx} 10{sup 4}-10{sup 6}), periods of {approx} 10-30 s, and amplitudes of @ 10-30% in soft X-rays and @ 0.5% in the optical. DNOs have never been detected in dwarf novae in quiescence, despite extensive searches; they appear on the rising branch of the dwarf nova, outburst, typically persist through maximum, and disappear on the declining branch of the outburst. The period of the oscillation also correlates with outburst state, decreasing on the rising branch and increasing on the declining branch. 2048 The dwarf nova SS Cygni routinely exhibits DNOs during outburst. Optical oscillations have been detected at various times with periods ranging from 7.3 s to 10.9 s. At soft X-ray energies, oscillations have been detected in {ital HEAO 1} LED 1 data at periods of @ 9 s and 11 s and in EXOSAT LE data at periods between 7.4 s and 10.4 s. Here, we describe the properties of the oscillations in the extreme ultraviolet (EUV) flux detected with the {ital Extreme Ultraviolet Explorer} (EUVE) Deep Survey (DS) photometer and Short Wavelength (SW) spectrometer during target-of-opportunity observations of SS Cyg in out- burst in 1993 August and 1994 June/July.
- Research Organization:
- Lawrence Livermore National Lab. (LLNL), Livermore, CA (United States)
- Sponsoring Organization:
- USDOE, Washington, DC (United States)
- DOE Contract Number:
- W-7405-ENG-48
- OSTI ID:
- 390468
- Report Number(s):
- UCRL-JC-124946; CONF-9608161-1; ON: DE96050505
- Resource Relation:
- Conference: 163. colloquium of the International Astronomical Union, Port Douglas (Australia), 15-19 Aug 1996; Other Information: PBD: Aug 1996
- Country of Publication:
- United States
- Language:
- English
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