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Probing Nearby Supernovae 2.8 Myr Ago: Investigating 60Fe Evidence in Ocean Crust Layers

Explore evidence for nearby supernovae 2.8 million years ago through 60Fe in ocean crust layers, dating with 10Be/9Be concentrations, and comparing with ice core data, correlating with climate effects.

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Probing Nearby Supernovae 2.8 Myr Ago: Investigating 60Fe Evidence in Ocean Crust Layers

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  1. Evidence for nearby SN 2.8Myr ago • 60Fe is produced mainly by type II SNe • half life 1.49 Myr • Look for 60Fe in ocean crust layers • Date the layers using 10Be/9Be concentrations • Produced by CR • Compare crust density with input flux • Normalize 60Fe uptake in the crust using 53Mn • Compare ice core with ocean crust concentrations • Further correct by Fe/Mn concentrations in the ocean water • Calculate 60Fe flux • Drop errors because they are getting really big • Wildly speculate about SNe distance

  2. Fig. 1: 60Fe/Fe concentrations vs. age

  3. Effects of nearby SN • Increased CR flux • 15%-ish for 100s of kyr • May affect climate • Correlation seen btwn CR flux and cloud cover • Maybe: CR deplete ozone, more UV gets through • Alters ocean crust dating using 10Be

  4. Fig 2: CR energy density vs. time

  5. Is this real? Solid Evidence • 60Fe spike • Crust layer dating • Absolute flux calibration • SN 60Fe output and transport Wild Speculation

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