Strömgren integral

In mathematics and astrophysics, the Strömgren integral, introduced by Bengt Strömgren^[1] while computing the Rosseland mean opacity, is the integral^[2]

${\displaystyle {\frac {15}{4\pi ^{4}}}\int _{0}^{x}{\frac {t^{7}e^{2t}}{(e^{t}-1)^{3}}}\,dt.}$

The Strömgren integral has applications to astrophysics.^[3]