Re: New ozone layer data article

[Tom Holtz <tholtz@geochange.er.usgs.gov>]

>>An exploding star about 185 trillion miles away would create enough gamma
>>radiation to thin the ozone for many years, he said.
>
>As I recall, this is less than 35 light-years.  A nova within that
>range would have left us at the middle of a huge and clearly visible
>shell of gas that has never, to my knowledge, been reported by any
>astronomers, nor have they identified any black holes or pulsars in
>that range.  I don't have a star atlas here at work, but I can't even
>recall a white dwarf star at that range, either.  Do we have any
>evidence for this besides a really spiffy analysis of what the
>radiation _might_ have done if it were close enough?  Do have any
>real candidates for the dead star(s) and what extinctions they are
>alleged to have participated in?

Since each star system independantly orbits the galactic core every hundred
million years or so, it is VERY unlikely that the remains of the
Permo-Triassic supernova (if any) would be anywhere near solar space 250
million years after the data.

                                
Thomas R. Holtz, Jr.                                   
tholtz@geochange.er.usgs.gov
Vertebrate Paleontologist in Exile                  Phone:      703-648-5280
U.S. Geological Survey                                FAX:      703-648-5420
Branch of Paleontology & Stratigraphy
MS 970 National Center
Reston, VA  22092
U.S.A.