Supernova Triggers For End-Devonian Extinctions?



The Late Devonian was a protracted period of low speciation resulting in biodiversity decline, culminating in extinction events near the Devonian-Carboniferous boundary. Recent evidence indicates that the final extinction event may have coincided with a dramatic drop in stratospheric ozone, possibly due to a global temperature rise.

Here we study an alternative possible cause for the postulated ozone drop: a nearby supernova explosion that could inflict damage by accelerating cosmic rays that can deliver ionizing radiation for up to ∼100 kyr. We therefore propose that end-Devonian extinction was triggered by one or more supernova explosions at ∼20 pc, somewhat beyond the ``kill distance'' that would have precipitated a full mass extinction. Nearby supernovae are likely due to core-collapses of massive stars in clusters in the thin Galactic disk in which the Sun resides. Detecting any of the long-lived radioisotopes \sm146, \u235 or \pu244 in one or more end-Devonian extinction strata would confirm a supernova origin, point to the core-collapse explosion of a massive star, and probe supernova nucleosythesis. Other possible tests of the supernova hypothesis are discussed.

Brian D. Fields, Adrian L. Melott, John Ellis, Adrienne F. Ertel, Brian J. Fry, Bruce S. Lieberman, Zhenghai Liu, Jesse A. Miller, Brian C. Thomas
Comments: 4 pages, no figures. Submitted to PNAS Brief Reports. Comments welcome. Creative Commons CC BY-NC-ND license
Subjects: High Energy Astrophysical Phenomena (astro-ph.HE); Solar and Stellar Astrophysics (astro-ph.SR); Geophysics (physics.geo-ph)
Cite as: arXiv:2007.01887 [astro-ph.HE] (or arXiv:2007.01887v1 [astro-ph.HE] for this version)
Submission history
From: Brian Fields
[v1] Fri, 3 Jul 2020 18:08:09 UTC (72 KB)

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