Our sun has a radius of 6.96 X 10^8 m. Sirius B is a white dwarf star that emits only 0.04 times the radiant power of the sun, even though it has a...

Our sun has a radius of 6.96 X 10^8 m. Sirius B is a white dwarf star that emits only 0.04 times the radiant power of the sun, even though it has a surface that is four times that of the sun. (a) What is the radius of Sirius B? (b) The mass of Sirius B is 2 X 10^30 kg, nearly the same as the sun s. What is the mass density of this white dwarf star? For comparison, the density of water is 1000-kg/m^3.