Supernovae and the Formation of Planetary Systems

Abstract

Immediately after the discovery in 1976 of strong evidence for live “Aluminum- 26 (26Al)” during the formation of certain portions of the Allende meteorite, the suggestion was made that this short-lived radioisotope may have been synthesized in a core-collapse (type II) supernova, transported across the inter- stellar medium by a supernova remnant, and injected into a dense molecular cloud core, which then collapsed as a result of the impact of the supernova remnant shock wave and subsequently formed our solar system. This theoretical hypothesis has been investigated in the intervening years with increasingly detailed hydrodynamical models of the interaction of supernova shock waves with target cloud cores, and it remains as a viable explanation for the source of the 26Al and various other short-lived radioisotopes discovered since 1976 in samples of the most primitive, unprocessed meteorites. While the formation processes of exoplanetary systems are much harder to decipher, based on our extremely limited information about their constituent planets and small bodies, much less their isotopic compositions, the supernova triggering and injection scenario is an attractive means for explaining the initiation of the formation of our own planetary system, and hence might be expected to be a formation mechanism for some currently uncertain fraction of the exoplanetary systems that we now know are common in our galaxy.