English (United Kingdom)

https://curated-unify.zendy.io/wp-json/zendy-region/v1/featured_content/oa?rat=en

https://curated-unify.zendy.io/wp-json/zendy-region/v1/highlighted_journal/

Global: Zendy Plus annual

Presents the access of premium content as premium feature

Premium Content

Presents the keyphrase highlighting as premium feature

Keyphrase Highlighting

Presents the summarisation as premium feature

Summarisation

Insights

Presents the pdf analysis as premium feature

PDF Analysis

Presents the zaia usage as premium feature

ZAIA

Global: Zendy Plus monthly

Global: Zendy Tools annual

Global: Zendy Tools monthly

Global: Zendy Free Plan

Near-Earth supernova blasts which engulf the solar system have left traces oftheir ejecta in the geological and lunar records. There is now a wealth of dataon live radioactive ${}^{60}$Fe pointing to a supernova at 3 Myr ago, as wellas the recent discovery of an event at 7 Myr ago. We use the availablemeasurements to evaluate the distances to these events. For the better analyzedsupernova at 3 Myr, samples include deep-sea sediments, ferromanganese crusts,and lunar regolith; we explore the consistency among and across thesemeasurements, which depends sensitively on the uptake of iron in the samples aswell as possible anisotropies in the ${}^{60}$Fe fallout. There is alsosignificant uncertainty in the astronomical parameters needed for thesecalculations. We take the opportunity to perform a parameter study on theeffects that the ejected ${}^{60}$Fe mass from a core-collapse supernova andthe fraction of dust that survives the remnant have on the resulting distance.We find that with an ejected ${}^{60}$Fe mass of $3\times10^{-5} M_\odot$ and adust fraction of 10%, the distance range for the supernova 3 Myr ago is $D \sim20 - 140$ pc, with the most likely range between $50 - 65$ pc. Using the sameastrophysical parameters, the distance for the supernova at 7 Myr ago is $D\sim 110$ pc. We close with a brief discussion of geological and astronomicalmeasurements that can improve these results.

Distances to Recent Near-Earth Supernovae From Geological and Lunar 60Fe