Finding atomic mass from temperature and velocity in astrophysics

[joekoviously]

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.

 

[KaiserBrandon]

which velocity did it give you? there's rms, most probable, or mean?

 

[joekoviously]

Mean translational velocity