The discussion centers on the presence of technetium-99 in red giants, particularly addressing how it can exist in these stars despite being heavier than the iron peak, which is typically considered the limit for energy-releasing fusion processes. The conversation explores theoretical frameworks and processes involved in nucleosynthesis, including the s-process and r-process.
Participants present multiple competing views regarding the formation of technetium-99 in red giants, with no clear consensus reached on the mechanisms involved or the implications of the iron peak.
Some limitations include the dependence on definitions of fusion processes and the assumptions regarding the conditions under which technetium-99 can form. The discussion does not resolve the complexities of the s-process and r-process or the implications of radioactive decay on the presence of technetium in stars.
My question arose from a straightforward problem showing how the technetium could not have been present in the star from the beginning, because of radioactive decay. To test my understanding, the technetium was formed in the star by the endoergic s-process. Elements up to the iron peak can be created by ordinary fusion. Probably an oversimplification on my part.mfb said:Iron/nickel is the limit where fusion releases energy. Fusion processes continue beyond that, they just don't release energy any more but need energy input.
https://en.wikipedia.org/wiki/R-process
https://en.wikipedia.org/wiki/S-process