Supernova Dust Evolution Probed by Deep-sea 60Fe Time History

Understand

There is a wealth of data on live, undecayed 60Fe ($t_{1/2} = 2.6 \ \rm Myr$) in deep-sea deposits, the lunar regolith, cosmic rays, and Antarctic snow, which is interpreted as originating from the recent explosions of at least two near-Earth supernovae.

• We use the 60Fe profiles in deep-sea sediments to estimate the timescale of supernova debris deposition beginning $\sim 3$ Myr ago.
• The available data admits a variety of different profile functions, but in all cases the best-fit 60Fe pulse durations are $>1.6$ Myr when all the data is combined.
• This timescale far exceeds the $\lesssim 0.1$ Myr pulse that would be expected if 60Fe was entrained in the supernova blast wave plasma.