The <effective temperature> is defined by $\boxed{L=4\pi R_*^2\sigma T_{\mathrm{eff}}^4}$, with <bolometric luminosity> $L$, photospheric <radius> $R_*$ and <Stefan-Boltzmann constant> $\sigma$. It is the blackbody <temperature> giving the same total <surface flux>, not a claim that each <spectral line> forms at that <temperature>.

Solution

Past exam of the short options paper shared by Prelims and Parts A and B of the physics course of the University of Oxford / 2017 / S2 / 2 / 1 / Solution

 Solution (source code)