Assume that you’ve taken a spectrum of a star, and you’d like to estimate the star’s size. Can you do it? Yes, if you also have a parallax angle for the star. This post quickly ties together different concepts to explain how observations (spectrum and parallax) can be used to estimate the size of a…
You can estimate a star’s size if you know its temperature and luminosity. To do this, assume that the surface of the star is a giant blackbody, then apply the Stefan-Boltzmann Law. The Stefan-Boltzmann law is discussed in section 5.2 of OpenStax Astronomy. To summarize, it states that the luminosity (total energy output as light)…
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