From: LARRY KLAES (ljk4_at_msn.com)
Date: Tue Jun 28 2005 - 07:16:11 PDT
Paper: astro-ph/0503625
replaced with revised version Mon, 27 Jun 2005 16:45:03 GMT (202kb)
Title: Climatic and Biogeochemical Effects of a Galactic Gamma-Ray Burst
Authors: Adrian L. Melott, Brian C. Thomas, Daniel P. Hogan, Larissa M.
Ejzak
(University of Kansas) and Charles H. Jackman (NASA Goddard)
Comments: 12 pages, 2 figures, in press at Geophysical Research Letters.
Minor
revisions, including details on falsifying the hypothesis
Subj-class: Astrophysics; Atmospheric and Oceanic Physics; Biological
Physics;
Geophysics; Space Physics; Populations and Evolution
It is likely that one or more gamma-ray bursts within our galaxy have
strongly irradiated the Earth in the last Gy. This produces significant
atmospheric ionization and dissociation, resulting in ozone depletion and
DNA-damaging ultraviolet solar flux reaching the surface for up to a decade.
Here we show the first detailed computation of two other significant
effects. Visible opacity of NO2 is sufficient to reduce solar energy at the
surface up to a few percent, with the greatest effect at the poles, which
may be sufficient to initiate glaciation. Rainout of dilute nitric acid is
could have been important for a burst nearer than our conservative nearest
burst. These results support the hypothesis that the characteristics of the
late Ordovician mass extinction are consistent with GRB initiation.
\\ ( http://arXiv.org/abs/astro-ph/0503625 , 202kb)
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