Supernova-Produced 53Mn on Earth

Abstract

For the time period from 1.5 to 4 Myr before the present we found in deep ocean ferromanganese crusts a Mn53 excess concentration in terms of Mn53/Mn of about 4×10-14 over that expected for cosmogenic production. We conclude that this Mn53 is of supernova origin because it is detected in the same time window, about 2.5 Myr ago, where Fe60 has been found earlier. This overabundance confirms the supernova origin of that Fe60. For the first time, supernova-formed Mn53 has been detected and it is the second positively identified radioisotope from the same supernova. The ratio Mn53/Fe60 of about 14 is consistent with that expected for a SN with a 11-25 M progenitor mass and solar metallicity.