I get that it creates heavier atoms by fusing lighter ones, and it happens during a supernova. But, what I don’t get is the process of it. And the teacher didn’t help either as they literally just read the module verbatim.
Thanks!
In: Chemistry
Stars fuse lower mass elements into higher mass. H > He, 3 x HE to Carbon and higher elements. There is a slow process by which elements are created by slow capture of neutrons. This means that the nucleus captures a free neutron and then undergoes decay which increases the atom number. Slow neutron capture might be once in 100 years.
As the lower mass fuel runs out, stars start to collapse and the heat of the core goes up which allows for burning of heavier elements. The limit is iron. All fusion releases energy to prop up the star until iron is formed. Fusion past iron requires energy input so once iron forms, the star explodes within seconds.
During a supernova, a lot of heat is generated and a lot of fusion can happen at once. And there are a lot of free neutrons which can be captured by heavy nuclei.
It is thought that heavier elements can be created through the r-process which is rapid neutron capture. It is rapid in that a neutron is captured by an atom and then it captures more neutrons before a decay can occur. The rate is perhaps 100 neutron captures per second. This will pump up the number of neutrons in the nucleus of the atom. This only happens in very neutron rich environments. The heavy, neutron rich atoms will undergo decay to something stable but still remain heavier elements.
The r-process will also occur during neutron star collisions. These collisions might seed the interstellar gas with most of the heavier elements.
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