Supernova-Produced <mml:math xmlns:mml="http://www.w3.org/1998/Math/MathML" display="inline"><mml:mrow><mml:mmultiscripts><mml:mrow><mml:mi>Mn</mml:mi></mml:mrow><mml:mprescripts/><mml:none/><mml:mrow><mml:mn>53</mml:mn></mml:mrow></mml:mmultiscripts></mml:mrow></mml:math> on Earth

Abstract

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

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