Amma-ray spectroscopy of the interstellar medium in the Orion complex.
Abstract
The COMPTEL telescope aboard the Compton Gamma-Ray Observatory (CGRO) has recently-detected gamma-ray emission from the Orion complex in the 3-7 range, which could be identified with the broad de-excitation lines of cosmic-ray carbon and oxygen nuclei, at 4.4 and 6.1 MeV, induced by energetic particle interactions. We show here that regions of massive star formation, which can be very efficient in accelerating low-energy cosmic-ray nulcei due to colliding stellar winds and multiple supernova explosions, are indeed expected to be prominent sources of gamma-ray lines from energetic nuclei that are extracted from the enriched hot medium and bombarding the ambient dense gas (clouds, shells). In particular, given the strong overabundance of oxygen in the supernova ejecta from massive stars as found in recent nucleosynthesis studies, the observed 3-7 MeV emission can readily be attributed to the de-excitation of accelerated oxygen nuclei (and their spallation products, such as carbon and nitrogen). We show that accompanying lines in the 1-3 MeV range are at the sensitivity level of COMPTEL.
- Publication:
-
Astronomy and Astrophysics
- Pub Date:
- March 1994
- Bibcode:
- 1994A&A...283L...1B
- Keywords:
-
- Astronomical Spectroscopy;
- Gamma Ray Astronomy;
- Gamma Rays;
- Interstellar Matter;
- Massive Stars;
- Orion Nebula;
- Star Formation;
- Stellar Winds;
- Cosmic Rays;
- Molecular Clouds;
- Nuclear Fusion;
- Supernovae;
- Astronomy