[ RadSafe ] Astrophysicists Report Radioactive Cobalt in Supernova Explosion

[Jaro Franta]

Andy et-al, FYI.....

http://science.nasa.gov/science-news/science-at-nasa/2014/26aug_localbubble/

Evidence for Supernovas Near Earth
August 26, 2014


 Jaro
^^^^^^^^^^^^^^^^^^^^^^^^^



-----Original Message-----
From: radsafe-bounces at health.phys.iit.edu
[mailto:radsafe-bounces at health.phys.iit.edu] On Behalf Of KARAM, PHILIP
Sent: September-09-14 10:13 AM
To: The International Radiation Protection (Health Physics) Mailing List
Subject: Re: [ RadSafe ] Astrophysicists Report Radioactive Cobalt in
Supernova Explosion

I remember looking at this as well - a high-energy gamma ray burst in the
Andromeda galaxy (about 3 million light-years away) could actually expose an
astronaut here to about a rad (10 mGy). 

There was some speculation in the late 1990s that periodic gamma ray bursts
might explain why we haven't been contacted by alien civilizations yet -
wondering if they periodically cause galaxy-wide mass extinctions. That
seems dubious, given that even a "long" gamma ray burst only lasts a few
seconds - enough to sterilize half a planet, but not the whole thing. Plus,
the thick dust and gas clouds in the galactic core would help to shield the
opposite side of the galaxy from the worst effects (although normal dust and
gas clouds in the disk are so scanty as to offer very little in the way of
attenuation).

There was also some speculation that neutrinos from supernovae might cause
mass extinctions - there are about 10^57 neutrinos produced during the
collapse of a giant star into a neutron star. But the interaction
cross-section of SN-spectrum neutrinos is too small and, even with one very
nearby, the dose would be too small to cause health problems. Interestingly,
the biggest concern from a nearby supernova will likely be ozone depletion
and the formation of opaque chemicals in the atmosphere. Some astronomers in
Texas (Scalo an Wheeler) suggested that a climate-altering supernova might
occur close enough to have a measurable impact every 10,000-100,000 years.

Andy 


P. Andrew Karam, PhD, CHP
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