X-ray emission from Trifid Nebula
Abstract
The Trifid Nebula is one of the best-studied astrophysical objects, a classical nebula of ionized gas from an O6V star glowing red light, and it is trisected by obscuring dust lanes. Our ROSAT/PSPC image for the first time reveals that the Trifid Nebula emits X-rays and its emitting region is ~ 7' diameter--as large as the HII region itself. %The only previously reported X-ray emission Three main X-ray peaks appear within ~ 4 pc diameter of diffuse emission, roughly spherical. The strongest peak has 2' size near the O star, but the centroid of the X-ray peak appears 25'' away from HD 164492. % which is larger than the PSPC point spread function. Thus the emission may be a shell surrounding the O star as observed in eta Carina, originating from the interaction of a stellar wind with a circumstellar shell. There are a few other X-ray peaks: along the northeastern dust lane and in the east, none of which coincide with any identified optical stars. The PSPC spectrum extracted from the entire Trifid nebula does not clearly distinguish between thermal, bremsstrahlung, and power-law models, due to lack of counts. However, all of these models imply the X-ray luminosity (0.3 - 2.4 keV) is greater than 0.2 - 3*E(34) ergs s(-1) . The diffuse emission is possibly thermal with a temperature of 0.3-1 keV, as in the other HII regions eta Carina and RCW 49. The strong stellar wind from an O star alone can inject an energy of ~ 10(36) ergs s(-1) into ISM; this energy can be converted to heat the ionized gas to X-ray temperature. While the global diffuse X-ray emitting region is similar to the optical HII region, the bright X-ray peaks coincide with the structures in the infrared, suggesting possible embedded stars and their interaction with the circumstellar medium.
- Publication:
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American Astronomical Society Meeting Abstracts #192
- Pub Date:
- September 1998
- Bibcode:
- 1998AAS...192.8304R