The Magnetic Field of the Intermediate Polar BG Canis Minoris
Abstract
Observations of the intermediate polar BG CMi show that the circular polarization increases rapidly from the optical toward IR wavelengths. These observations can be understood as the emission from a large magnetic polar cap consisting of hot plasma heated to an accretion shock temperature of 10 keV and an underlying photosphere at 0.01 keV. Reasonable fits to the polarization observations can be obtained with polar fields in the range B = 2-10 MG. Constraints from X-ray observations suggest that the field is likely to be around 4 MG. The polarization in the optical band is mainly due to free-free emission in a magnetic field, while the polarization in the J and H bands is mainly due to cyclotron emission. Dilution by the companion star may allow B up to about 6 MG. Implications of these results for the understanding of the evolution of magnetic cataclysmic variables are discussed.
- Publication:
-
The Astrophysical Journal
- Pub Date:
- February 1990
- DOI:
- 10.1086/185656
- Bibcode:
- 1990ApJ...350L..13C
- Keywords:
-
- Cataclysmic Variables;
- Circular Polarization;
- Magnetic Field Configurations;
- Stellar Evolution;
- Stellar Magnetic Fields;
- Stellar Mass Accretion;
- Cyclotron Radiation;
- High Temperature Plasmas;
- Magnetic Flux;
- Shock Heating;
- Stellar Models;
- Astrophysics;
- POLARIZATION;
- RADIATION MECHANISMS;
- STARS: ACCRETION;
- STARS: BINARIES;
- STARS: MAGNETIC;
- STARS: NOVAE