Disappearance of periodic X-ray minima in AM Her.
Abstract
Optical, soft X-ray, and medium energy X-ray measurements taken during an unusual high state of AM Her are reported. The X-ray and secondary optical minima disappeared from the light curve. The X-ray flux varied perodically. In each X-ray band, the flux during the expected phase of minimum was approximately the same as the average during the rest of the cycle. The optical and medium energy X-ray fluxes were at all-time highs; however, the soft X-ray flux was low by a factor of 3 compared to the nominal high state. This change in the ratio of medium to soft X-ray flux is difficult to fit into the standard scenario for AM Her, where soft X-rays are interpreted as reprocessed optical and medium energy X-ray flux. The peculiar light curve of AM Her was probably caused by a small shift in the position of the accretion column with respect to the rotation axis, so that the normal grazing eclipse of the accretion column did not take place.
- Publication:
-
Astronomy and Astrophysics
- Pub Date:
- February 1987
- Bibcode:
- 1987A&A...173...95P
- Keywords:
-
- Light Curve;
- Stellar Mass Accretion;
- X Ray Stars;
- Accretion Disks;
- Flux Density;
- Stellar Spectra;
- X Ray Spectra;
- Astrophysics