"b" == beavith writes:

BC Elsewhere I read it is nickel-60, decaying from iron-60, that is
BC found in meteorites on earth. Is this true? Are there any other
BC elements that would provide the telltale signs of having been
BC formed in massive stars?

There's been a long standing puzzle that aluminum-26 decay
products also are found in some meteorites. Aluminum-26 has a very
short half-life (...) which has been interpreted as
implying that a massive star must have gone supernova within a few
million years of the formation of the solar system. More recently,
however, Frank Shu and others have proposed that the X-ray activity
of the young Sun may have been enough to produce the Al-26. It
would be interesting to hear that team's thoughts on this new
proposal.

b something sounds fishy...
[...]
b from the physics i understand, xrays can't cause nuclear reactions,
b so i'm hard pressed to understand how a youthful xray intense star
b can produce Al26, unless its being produced in the star and blowing
b out of it with the solar wind...

I think the 26-Al is thought to be more a product of cosmic-ray
irradiation, resulting from the X-ray activity. (Admittedly, my
earlier post wasn't clear on this.) A short abstract along these
lines is URL:
http://adsabs.harvard.edu/cgi-bin/np...AS...197.0201S
, and I think more detail is in Shu et al. (2001, URL:
http://adsabs.harvard.edu/cgi-bin/np...pJ...548.1029S
) and Gounelle et al. (2001, URL:
http://adsabs.harvard.edu/cgi-bin/np...pJ...548.1051G
).

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