Chandra Low Energy Transmission Grating Spectrum of SS Cygni in Outburst
Abstract
We have fitted the Chandra Low Energy Transmission Grating (LETG) spectrum of SS Cygni in outburst with a single-temperature blackbody suffering the photoelectric opacity of a neutral column density and the scattering opacity of an outflowing wind. We find that this simple model is capable of reproducing the essential features of the observed spectrum with the blackbody temperature Tbl~250+/-50 kK, hydrogen column density NH~5.0+2.9-1.5×1019cm-2, fractional emitting area f~5.6+60-4.5×10-3, boundary layer luminosity Lbl~5+18-3×1033ergss-1, wind velocity v~2500kms-1, wind mass-loss rate Mw~1.1×1016gs-1, and arbitrary values of the wind ionization fractions of 20 ions of O, Ne, Mg, Si, S, and Fe. Given that in outburst the accretion disk luminosity Ldisk~1×1035ergss-1, Lbl/Ldisk~0.05+0.18-0.03, which can be explained if the white dwarf (or an equatorial belt thereon) is rotating with an angular velocity Ωwd~0.7+0.1-0.2 Hz, hence Vrotsini~2300kms-1.
This paper is dedicated to the memory and accomplishments of my colleague and friend Janet Akyüz Mattei, who died on 2004 March 22 after a long battle with acute myelogenous leukemia. Her passing is a great loss to the astronomical community, both amateur and professional.- Publication:
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The Astrophysical Journal
- Pub Date:
- July 2004
- DOI:
- 10.1086/421438
- arXiv:
- arXiv:astro-ph/0403691
- Bibcode:
- 2004ApJ...610..422M
- Keywords:
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- Accretion;
- Accretion Disks;
- Stars: Binaries: Close;
- Stars: Novae;
- Cataclysmic Variables;
- Stars: Individual: Constellation Name: SS Cygni;
- X-Rays: Binaries;
- Astrophysics
- E-Print:
- 5 pages including 3 encapsulated postscript figures