Editing Equipartition theorem (section)

===Star formation===
The same formulae may be applied to determining the conditions for [[star formation]] in giant [[molecular cloud]]s.<ref>{{cite book |last1=Carroll |first1=Bradley W. |last2=Ostlie |first2=Dale A. |year=1996 |title=An Introduction to Modern Stellar Astrophysics |publisher=Addison–Wesley |location=Reading, MA |isbn=0-201-59880-9 }}</ref> A local fluctuation in the density of such a cloud can lead to a runaway condition in which the cloud collapses inwards under its own gravity. Such a collapse occurs when the equipartition theorem—or, equivalently, the [[virial theorem]]—is no longer valid, i.e., when the gravitational potential energy exceeds twice the kinetic energy
<math display="block">\frac{3G M^{2}}{5R} > 3 N k_\text{B} T.</math>
Assuming a constant density {{math|''ρ''}} for the cloud
<math display="block">M = \frac{4}{3} \pi R^{3} \rho</math>
yields a minimum mass for stellar contraction, the Jeans mass {{math|''M''<sub>J</sub>}}
<math display="block">M_\text{J}^{2} = \left( \frac{5k_\text{B}T}{G m_{p}} \right)^{3} \left( \frac{3}{4\pi \rho} \right).</math>
Substituting the values typically observed in such clouds ({{math|1=''T'' = 150 K}}, {{math|1=''ρ'' = {{val|2e-16|u=g/cm3}}}}) gives an estimated minimum mass of 17 solar masses, which is consistent with observed star formation. This effect is also known as the [[Jeans instability]], after the British physicist [[James Hopwood Jeans]] who published it in 1902.<ref>{{cite journal | last = Jeans | first = JH | author-link = James Hopwood Jeans | year = 1902 | title = The Stability of a Spherical Nebula | journal = [[Philosophical Transactions of the Royal Society A]] | volume = 199 | issue = 312–320 | pages = 1–53 | doi = 10.1098/rsta.1902.0012 | bibcode=1902RSPTA.199....1J| doi-access =  }}</ref>