9 BILLION years after the Creation...

Finally, there are low mass stars with plenty of Fe that have entered the final stage of the Asymptotic Giant Branch. The INCOMPARABLE PHYSICIST is ready to test out his "Slow Neutron Capture Process" for nuclear synthesis.

WATCH CAREFULLY now as a low mass AGB star undergoes a THERMAL PULSE. A thin shell of helium around the core ignites which expands the shell, cooling the hydrogen above it and turning off its fusion.

THEN, the helium fuel runs out, causing the shell to contract which heats up the hydrogen above, causing it to ignite, producing more helium, which replenishes the depleted shell beneath it.

The star is PULSING at super slow frequency...

While the helium shell is being replenished, pockets of 13C and 22Ne go through a period where they absorb alpha particles and produce significant quantities of free neutrons.

The seed Fe that came from the ISM and other heavier nuclei that are further along the s process, absorb these free neutrons to form heavier isotopes. If those isotopes are stable they proceed to the next isotope. If they are unstable then beta decay will ensue, moving the nucleus to the next higher atomic number.

The process is SLOW but step by step these nuclei move along the "Valley Of Stability", synthesising all the elements from Fe to Pb where the process terminates in a loop.

Eventually the star dies, ejecting these products into the ISM, leaving a white dwarf with a C-O core.

Because there are SO MANY MORE low mass stars that use this modest seeming "s-process" than there are neutron star mergers that use the far more impressive and efficient "r-process", the amount of high mass elements released into the ISM by these two mechanisms is roughly similar.

Furthermore: Virtually ALL the elements in the Universe from Strontium upward are made using just these two mechanisms.