Gamma-ray lines from the Orion complex

Abstract

We show that the 4.44 and 6.13 MeV line emission observed with COMPTEL from Orion is consistent with gamma ray spectra consisting of a mixture of narrow and broad lines or spectra containing only broad lines. We employed several accelerated particle compositions and showed that the current COMPTEL data in the 3--7 MeV region alone cannot distinguish between the various possibilities. However, the COMPTEL upper limits in the 1--3 MeV band favor a composition similar to that of the winds of Wolf-Rayet stars of spectral type WC. The power dissipated by the accelerated particles at Orion is about 4 $\times$ 10$^{38}$ erg s$^{-1}$. These particles are not expected to produce significant amounts of $^{26}$Al.