I suggest
isotope separation by gravitation.
Gravitation can be very effective. 30km/s (the orbital speed around our Sun at Earth's distance, not the ridiculous human-made centrifuges) make a difference in kinetic energy of 7*10
-19J per neutron, or
500 times kT at 100K. Few details more at Saposjoint.net, subforum Astronomy, topic "Isotopic abundance".
As far as I ignore (I'm not in this field) astronomers still look for inefficient chemical processes to explain differences in isotopic composition, though gravitation is hugely more efficient. Even if gravitation is hampered by mixing processes, remnants of its effect can overshadow chemical processes.
This would have important implications... IF I'm not too mistaken
! Isotopic composition is an argument for scenarios of our Solar system, galaxies, and maybe even type I and type II populations. Or consider Jupiter, with 60km/s escape velocity and its upper atmosphere at 200K, where heavier isotopes seem to be too scarce.
One other example here
http://sci.esa.int/science-e/www/object/index.cfm?fobjectid=49008
Observed oxygen, a heavier atom, is too scarce in molecular clouds, but reappears when stars lit up. Could oxygen coalesce before hydrogen for being heavier? In our upper atmosphere, which is much smaller but denser and hot, gravitation does segregate lighter elements.
What I did NOT check, and won't:
- Under what conditions (dilute cold gas?) gravitation acts fast enough. Faster than the separation into a sun and planets for instance. This would be a slow diffusion process, but adequate conditions at some evolution time could make it fast enough.
- What conditions (turbulence) prevent this separation, and how much separation remains
- If stars with a metal-rich chromosphere are more turbulent (!) and contain more heavy isotopes
- Whether this ideas was already explored and dismissed...
So nearly everything remains to do if you like the idea, and the size of the project can vary.
Marc Schaefer, aka Enthalpy
