MASSIVE SUPERNOVAE, ORION GAMMA-RAYS, AND THE FORMATION OF THE SOLAR-SYSTEM

We discuss the source of the enhanced carbon and oxygen low-energy cos mic-ray flux in the Orion star-forming region and attribute it to the acceleration of the surface layers of a massive supernova, probably of Type Ib. The gamma rays from Orion are produced by that fast CO eject a. In this model there would be few Orion-like gamma-ray sources in th e Galaxy at any one time. We also postulate that a massive supernova p roduced the short-lived extinct radioactivities injected into the mole cular cloud core that produced the solar system. We find that relative to Al-26 the other short-lived extinct radioactivities are excessivel y produced in massive supernovae but are likely to be more attenuated by postexplosion fallback than Al-26. This is a revival of the superno va trigger hypothesis; to obtain the correct dilutions of the extinct radioactivities, the distance from the supernova to the impacted molec ular cloud core must be a few parsecs, and the effective projected col lecting area of the cloud must be significantly less than normal core radii.