Transcript: Some stars in the sky, somewhat hotter than the Sun with temperatures of 5 thousand to 10 thousand Kelvin, have very low luminosities in the range of one-hundredth to one-thousandth the Sun’s luminosity. Application of the Stephan-Boltzmann Law shows that they must be physically small with sizes less than a tenth the size of the Sun, perhaps as low as one-hundredth the size of the Sun. These stars are called white dwarfs.