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B.C. Thomas (Washburn University), A.L. Melott, D.P. Hogan (University of Kansas)
It has been suggested by several authors (e.g. Ruderman 1974; Reid et al. 1978; Ellis & Schramm 1995) that a relatively nearby supernova (SN) explosion could have significant effects on life on the Earth. A primary terrestrial effect of such an encounter would be depletion of the ozone layer, thereby increasing the flux of solar UVB radiation at the Earth's surface. At least one quantitative study of the effects on ozone by SN at various distances has been conducted (Gehrels et al. 2003). There is direct geochemical evidence for at least one SN event at a distance of around 40 pc at about 2.8 Myr ago (Fields 2004; Knie et al. 1999, 2004; Benitez et al. 2002). In this work we examine a suite of effects of such a SN at a distance of 30pc. We investigate ozone depletion, the subsequent increase of solar UVB reaching the Earth's surface, and the biological impact of this increased UVB. We find maximum localized ozone column density depletion of about 10% lasting a few months, an increase of around 1% in UVB irradiance in certain locations, and about 5% increase in relative DNA damage. While this level of effect is unlikely to be responsible for a large scale die-off, increases in the mutation rate are likely, possibly with interesting evolutionary or ecological implications. This work is supported in part by NASA Astrobiology grant NNG04GM41G.
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Bulletin of the American Astronomical Society, 37 #4
© 2005. The American Astronomical Soceity.