Hertzprung-Russel Diagram

This is a Hertzprung-Russel diagram showing stellar absolute magnitude (how luminous a star is) versus "color-magnitude" (B-V; how red or blue a star is). Stellar data from the HIPPARCOS (black dots) and Gliese (gray dots) catalogues were used. Thus this HR diagram is biased toward nearby (Gliese) or bright (HIPPARCOS) stars. The color bar indicates temperature in units of 10^3 Kelvin. The Main Sequence and Giant Branch are indicated, as well as the primary stars of interest for the Trinity College Dublin (Ireland) Astrophysics Research Group (the Sun, Betelgeuse and EG Andromeda). As you can see, the Sun is quite an average star. This diagram will be published in my PhD thesis (Higgins, 2012; submitted).