Creation of heavy elements: r and s process

[Gideon]

Hi, I'm studying my astronomy course at the moment and i have question about the r- and s-process. As I understand it, in the r-process, the time between capturing two neutrons is shorter than the averge beta decay half life, right? So I'm guessing there have to be a lot of neutrons around for the r process to take place. But where do all these neutrons come from?

 

[Labguy]

Hi, I'm studying my astronomy course at the moment and i have question about the r- and s-process. As I understand it, in the r-process, the time between capturing two neutrons is shorter than the averge beta decay half life, right? So I'm guessing there have to be a lot of neutrons around for the r process to take place. But where do all these neutrons come from?

It is mostly ionized H atoms, simply protons, among free electrons (=plasma) that gets the stars going in the core. See mainly pages 3-5 of this link:

http://www.genesismission.org/educate/scimodule/SunandSolar/Final%20Linked%20SSW/6AppendicesCari/a.pdf

 

[Astronuc]

Neutrons can come from certain fusion reactions of light isotopes, and from spallation reactions in the heavier nuclides.

See also - https://www.physicsforums.com/showpost.php?p=506354&postcount=7, which mentions reactions concerning production of superheavy elements.

 

[Nereid]

Welcome to Physics Forums, Gideon!

Others have already answered your question, in one sense; perhaps (however) you meant something like 'in what environments are such floods of neutrons likely to occur?'

Supernovae, of the core collapse kind - can you now find out why such environments are expected to be so 'neutron-rich'?