Abstract:
The presence of technetium (Tc) with its short-lived isotopes in the atmospheres of AGB stars is regarded as strong evidence for recent occurrence of s-process nucleosynthesis in stars. However there is seen to be an opposite correlation between matallicity and the Tc present in most of these stars suggesting that one most also invoke alternative mechanism for Tc production. Supernovae are sites for production of neutron rich r-process isolates such as Th-22, Zr-99, etc. Can lead to significant yields of Tc-99 of about five percent. Also Mev neutrino interactions with MO and Zr isotopes can again give Tc isotopes by spallation reactions. Again AGB stellar atmospheres containing r-process elements and subjected to gamma photons and neutrinos from enhanced CNO shell buring can also produce Tc isotopes.
