Absolute Magnitude

Magnitude an object would have if placed at a distance of exactly 10 parsecs (= 32.6 light years). A supergiant star might have an absolute magnitude of -8 whereas a dim red dwarf might have an absolute magnitude of +16. The Sun has an absolute magnitude of +4.8 – about half way between the two extremes. To convert the observed brightness of a star (the apparent magnitude, m, to an absolute magnitude, we need to know the distance in parsecs d, to the star. Alternatively, if we know the distance and the apparent magnitude of a star, we can calculate its absolute magnitude. Both calculations are made using:

The quantity m – M is known as the distance modulus.

Some or all content above used with permission from J. H. Wittke.