One way to calculate the radius of a star is to use its luminosity and temperature and assume that the star radiates approximately like a blackbody. astronomers have measured the characteristics of central stars of planetary nebulae and have found that a typical central star is 16 times as luminous and 20 times as hot (about 110,000 k) as the sun. find the radius in terms of the sun’s. how does this radius compare with that of a typical white dwarf?