Technetium-99 was detected in a red giant star through spectroscopy, raising questions about its formation beyond the iron peak, where fusion typically ceases to release energy. The discussion highlights the s-process, a neutron capture process that allows for the creation of heavy elements like technetium within stars. It is established that technetium could not have originated in the star due to radioactive decay, confirming its formation during the endoergic s-process. This process requires energy input, contrasting with the energy-releasing fusion of lighter elements up to iron and nickel.
PREREQUISITESAstronomers, astrophysicists, and students of nuclear physics interested in stellar evolution and nucleosynthesis processes.
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