Hello, I am currently having a problem on a question in astrophysics. It is asking to find the atomic mass number of a substance given only the temperature and velocity of the substance. I cannot seem to come up with an equation relating them together. The closest I have come is deriving the line of sight velocity dispersion which I don't think applies. That equation I came up with is: (simga) = (kT/(mu)(mass proton))^(1/2) Any help or insight would be greatly appreciated. Thank you in advance, Joe.