The isolated neutron star candidate RBS1223 (1RXS J130848.6+212708)
Abstract
In the ROSAT Bright Survey (RBS) we have almost completely optically identified the brightest ~ 2000 high-galactic latitude sources from the ROSAT All-Sky Survey Bright Source Catalogue (1RXS). A small number of sources has empty X-ray error circles on optical images. ROSAT HRI follow-up observations of RBS1223 (=1RXS J130848.6+212708), a soft object with extreme X-ray to optical flux ratio, have confirmed a relatively bright X-ray source, whose position could be determined to an accuracy of 1.6 arcsec (90%) due to the presence of a nearby, X-ray detected bright star. Deep Keck R- and B-band images of the field were taken, but the refined X-ray error circle remains empty to a limiting magnitude B ~ 26(m) . With an X-ray to optical flux ratio of log (f_X/f_opt)>4.1 this object is almost certainly an isolated neutron star, similar to the two so far best-known examples RX J1856.4-3754 and RX J0720.4-3125. We discuss limits on the number of similar objects in the RBS catalogue.
- Publication:
-
Astronomy and Astrophysics
- Pub Date:
- January 1999
- DOI:
- 10.48550/arXiv.astro-ph/9811326
- arXiv:
- arXiv:astro-ph/9811326
- Bibcode:
- 1999A&A...341L..51S
- Keywords:
-
- ACCRETION;
- ACCRETION DISKS;
- STARS: NEUTRON;
- X-RAYS: STARS;
- STARS: INDIVIDUAL: RBS 1223;
- Astrophysics
- E-Print:
- 4 pages, 3 figures, Astron. Astrophys. Lett., in press, see also http://www.aip.de:8080/~preprint/preprints/1998/1998_rbs1223.html