Consider two stars Gliese 667C and Betelguese that have the same spectral class
M1, and therefore the same surface temperature.
Gliese 667C is on the main
sequence, and Betelguese is on the supergiant branch of the HR diagram. Suppose
we can estimate their distances by independent means, so we know their intristic
luminosities. The M1 supergiant has the average luminosity L$G
= 1000001 Sun,
while the main sequence star has the luminosity of LW3
= 0.0141 Sun-
Given
that the radius of Gliese 667C star is about 300000 km, find the radius of the
Belelguese. Express your result both in km and in AU.