A Possible Isolated Neutron Star near the CrA Molecular Cloud
Abstract
It is thought that there are some 10(8) isolated neutron stars in our galaxy. These should be bright soft X-ray/EUV sources, and were expected to make a significant contribution to the ROSAT PSPC and WFC source catalogs. To date they have not. In a ROSAT PSPC survey of the Corona Australis molecular cloud, we discovered a bright (3 c s(-1) ), soft (kT=60 eV) X-ray source. The source was also seen in the ROSAT all sky survey, two years prior to the pointed observation, with the same count rate and spectrum. The column of N_H ~ 10(20) cm(-2) suggests a distance comparable to the 120 pc to the CrA molecular cloud. There is no obvious optical counterpart; all the stars in the field brighter than V ~ 19 are red. (F_x)/(F_v) exceeds unity, and may exceed 2000. The observable parameters are comparable to those predicted by Blaes & Madau (ApJ 403, 690, 1993) for a neutron star accreting isotropically from the interstellar medium. The emitting area is 260 km(2) at a distance of 100 pc. We will present arguments that this object is indeed an example of an isolated neutron star. If so, the expected UBV magnitudes are 25.7, 27.1, and 27.4, respectively. A recent ROSAT HRI position should significantly decrease the positional uncertainty and aid in the search for an optical counterpart.
- Publication:
-
American Astronomical Society Meeting Abstracts
- Pub Date:
- December 1994
- Bibcode:
- 1994AAS...185.7813W