The parallax method fails beyond about 250 parsecs because the angle becomes too small to measure. Astronomers must therefore use the inverse-square law , comparing apparent brightness and luminosity to find the distance of more remote stars.
Stars have a wide range of surface temperature as measured by their color.
According to Wien s law, hot stars will be blue and cool stars red. Once the temperature and luminosity of a star are known we can calculate its radius with the Stefan-Boltzmann law. We can find a star s composition by looking at the lines in its spectrum. We can find a star s mass if it is in a binary system two stars bound together gravitationally. For such stars, the orbital period and size when combined in the modified form of Kepler s third law give the masses of the orbiting stars.