Stars send out radiation over a wide range of frequencies, and the detection of such radiation gives information about their surface properties. For one star only, the Sun, there is additional information from the central regions, because there is the possibility of detecting certain sub-atomic particles, called neutrinos that are produced in the nuclear reactions. […]

In the previous chapter we gave an outline of the measurements astronomers can make to find out the properties of stars. Most off the mass of a galaxy is in stars of one type or other This chapter shows how mathematicians, physicists and theoretical astronomers have used the observations in order to deduce how stars […]