Tree rings may hold clues to impacts of distant supernovas on Earth
University of Colorado at Boulder, November 11, 2020
https://www.sciencedaily.com/releases/2020/11/201111144400.htm
Tree rings may hold clues to earthly impacts of distant supernovas
https://www.sciencealert.com/traces-of-supernovae-could-be-locked-in-the-rings-of-ancient-trees
https://sciencesprings.wordpress.com/2020/11/14/from-university-of-colorado-boulder-tree-rings-may-hold-clues-to-earthly-impacts-of-distant-supernovas/
The paper is;
Brakenridge, G.R., Solar system exposure to supernova γ
radiation. International Journal of Astrobiology, pp.1-14.
Yours,
Paul H.