Visual and Infrared Photometry of the Ultrashort Period Dwarf Nova HT Cassiopeiae
Abstract
This paper presents simultaneous visual (V) and infrared (H) photometry of the eclipsing dwarf nova binary HT Cas during two eclipses in October 1985, and infrared (JHK) photometry out of eclipse in January 1986. These are the first infrared observations of this object. They require that the red dwarf is fainter than Fν = 0.5 mJy at H(H = 15.7), and that the system is at least 215 pc away, for a red dwarf radius of RR = 0.15 R_sun;. At this distance, the white dwarf has a brightness temperature at V of Tb = 26000K. The accretion disk around the white dwarf is highly variable from epoch to epoch: it was 70% brighter at H in January 1986 than in October 1985. Such variability in a quiescent system is unprecedented. The disk consisted of optically thin material in January, when it had a kinetic temperature of Tkin = 10000 - 20000K, and was most likely optically thin in October too.
- Publication:
-
The Astronomical Journal
- Pub Date:
- November 1987
- DOI:
- 10.1086/114565
- Bibcode:
- 1987AJ.....94.1291B
- Keywords:
-
- Astronomical Photometry;
- Dwarf Novae;
- Eclipsing Binary Stars;
- Infrared Photometry;
- Accretion Disks;
- Brightness Temperature;
- Light Curve;
- Red Dwarf Stars;
- Stellar Color;
- Variability;
- White Dwarf Stars;
- Astrophysics;
- STARS: NOVAE