ROSAT Observations of the Chamaeleon Star Forming Cloud
Abstract
Two adjacent soft X-ray images of the nearby Chamaeleon I cloud were obtained in February-March 1991 with the ROSAT PSPC detector. Exposures were 6 ksec, giving an on-axis sensitivity about 4 times 10(-14) erg/s/cm(2) in the 0.1-2 keV band, or 9 times 10(28) erg/s at a distance of 140 pc. The quality of the images are superb, with 70 sources confidently detected and 20 additional possibly detected. About 40 sources have absolute positional accuracies better than 10('') , permitting unambiguous optical identification with stars on digitized SERC/ESO survey plates. By comparison, previous Einstein images (Feigelson and Kriss 1989) are several fold worse in both sensitivity and resolution. Firm associations between X-ray sources and optical stars show that 23 of the 58 previously known cloud members (Gauvin and Strom 1991) are detected, consistent with previous X-ray luminosity functions of low mass pre-main sequence stars. The more massive stars are particularly prominent in X-rays. Of greater interest is the discovery of at least 18 new X-ray emitting stars ranging from 10-19 magnitude, considerably increasing its pre-main sequence population. The `weak' T Tauri population in the cloud is at least equal to the `classical' T Tauri population. X-ray maps, optical finding charts, X-ray emission in the Hertzsprung-Russell diagram, and correlations between X-ray and optical/infrared properties will be shown and discussed.
- Publication:
-
American Astronomical Society Meeting Abstracts #180
- Pub Date:
- May 1992
- Bibcode:
- 1992AAS...180.4315F