The early light curve of A 0620-00.
Abstract
The Ariel-5 All-Sky Monitor measured the 3-6 keV X-ray intensity of 0620-00 for two days shortly after peak emission in August 1975, and continuously throughout September 1975. The effective exposure each day for this source (and every other source in the 80% of the celestial sphere covered by the monitor) is approximately 250 sq cm sec. The light curve obtained through October 1 (when the spin axis was again pointed to A0620-00) is shown. The intensity difference at maximum is obviously a manifestation of the very soft spectrum of the source. Clearly, A0620-00 was approximately four times as bright as Sco X-1 at maximum in the band 3-6 keV. The decay is quite smooth, but cannot be fit with a single e-folding time. The interval between the early All-Sky Monitor points and the onset of continuous coverage has an inferred e-folding time of 22 days, but it is continually increasing throughout September. A0620-00 is apparently similar in its X-ray character to the very strong, long-lasting transient X-ray sources which presently number six. In contrast, only three can be sensibly reconciled with the lower-intensity, shorter-duration hard-spectrum transients which have been found to pulse on a time scale of minutes.
- Publication:
-
NASA Special Publication
- Pub Date:
- 1976
- Bibcode:
- 1976NASSP.389..311K
- Keywords:
-
- Light Curve;
- Novae;
- X Ray Sources;
- All Sky Photography;
- Ariel Satellites;
- Binary Stars;
- Emission Spectra;
- Stellar Radiation;
- Astronomy