# The mass-radius relation of a white dwarf

I have a mass of 1.3 solar masses (For a white dwarf), and my aim is to find the radius of this mass.

I have used the relation R $$\propto$$ $$M^{\frac{-1}{3}}$$.

From here I multiplied using the solar mass and radius.

*$$R_D =$$ Radius of white dwarf, $$R_S$$ = Radius of the sun.

$$\frac{R_D}{R_S}$$ = $${(\frac{1.3M_S}{M_S}})^{\frac{-1}{3}}$$

After multiplying across by $$R_S$$ I get a value of $$R_D$$ = 0.916 $$R_S$$ which is incorrect.

I would appreciate if someone could point out where I'm going wrong.