Supernova-Produced 53Mn on Earth

For the time period from 1.5 to 4 Myr before the present we found in deep ocean ferromanganese crusts a ⁵³Mn excess concentration in terms of ⁵³Mn/Mn of about 4 ×10^-14 over that expected for cosmogenic production. We conclude that this ⁵³Mn is of supernova origin because it is detected in the same time window, about 2.5 Myr ago, where ⁶⁰Fe has been found earlier. This overabundance confirms the supernova origin of that ^<60Fe. For the first time, supernova-formed ⁵³Mn has been detected and it is the second positively identified radioisotope from the same supernova. The ratio ⁵³Mn/⁶⁰Fe of about 14 is consistent with that expected for a SN with a 11 - 25 M_⊙ progenitor mass and solar metallicity.