Simultaneous Extreme-Ultraviolet and Infrared Observations of the Eclipsing Polar HU Aquarii
Abstract
We present simultaneous EUV and infrared (J, K) observations of the polar HU Aquarii obtained during 1998 August when the star was in a high mass accretion state. EUV and IR light curves and EUV spectra are presented and compared with previous observations. The accretion region on the white dwarf has increased in temperature (124,000 to 240,000 K) and radius (0.04RWD to 0.06RWD) compared with previous EUV observations made during low mass accretion states. The EUV and IR photometric observations are shown to have a similar appearance as a function of orbital phase. The EUV photometry shows rapid changes and provides evidence for mass accretion via blobs. The high-state IR light curves present an asymmetric double-humped shape with J=14.8 and K=14.1. We applied an ellipsoidal model fit to the observations, and the result indicates that the cause of the modulated shape is due to both ellipsoidal variations from the Roche lobe filling secondary star and a complex flux combination probably dominated at all orbital phases by cyclotron emission. The source of maximum cyclotron emission appears to be in the accretion column high above the white dwarf surface.
- Publication:
-
The Astronomical Journal
- Pub Date:
- January 2002
- DOI:
- 10.1086/324640
- arXiv:
- arXiv:astro-ph/0109457
- Bibcode:
- 2002AJ....123..420H
- Keywords:
-
- Stars: Binaries: Eclipsing;
- Stars: Binaries: General;
- Stars: Novae;
- Cataclysmic Variables;
- Stars: Individual: Constellation Name: HU Aquarii;
- Stars: Magnetic Fields;
- Astrophysics
- E-Print:
- Accepted for publication in AJ