Gas Temperature and star formation

[damasgate]

If gas has to be cooled below, say, 100 K, in order for stars to form, what is the highest redshift
for star formation?

What would be the necessary equations to solve this problem??

[ideasrule]

I don't understand. In order for stars to form, you need enough hydrogen at and a sufficiently high temperature, in the order of millions of degrees. What does this have to do with redshifts, or cooling the gas?

[damasgate]

It's somehow relating it to the CMB, What I'm not understanding is the procedure to solve the question. Do I use Friedmann equations???

full text

Gas temperature and star formation. Gas, immersed in the CMB photon bath
continuously, behaves like the Earth in problem 1 and is heated up to a temperature
comparable to the CMB temperature. CMB photons are a blackbody with temperature 
3000K at a redshift of 1100. And the blackbody has been cooling down as T(t) / 1=a(t),
since the expansion of the universe redshifts the wavelengths of CMB photons. If gas has
to be cooled below, say, 100 K, in order for stars to form, what is the highest redshift
for star formation? For reference, the galactic halo star HD 1523-0901 is determined to
have an age of 13:2 Gyrs, corresponding to a redshift of approx 10 in our current cosmological
model.

[Chalnoth]

If gas has to be cooled below, say, 100 K, in order for stars to form, what is the highest redshift
for star formation?

What would be the necessary equations to solve this problem??
You only need to know the redshift and temperature at one point, and the fact that temperature scales linearly with redshift (well, z+1). That is, if you halve the redshift, you halve the temperature.

This sort of idea is sensible, by the way, because a hot gas will not collapse to form stars. A gas needs to cool sufficiently before its atoms are slow enough to fall into gravitational potential wells.