Absolute Magnitude

Magnitude an object would have if placed at a distance of exactly 10 parsecs (= 32.6 light years). A supergiant starSelf-luminous object held together by its own self-gravity. Often refers to those objects which generate energy from nuclear reactions occurring at their cores, but may also be applied to stellar remnants such as neutron stars. might have an absolute magnitude of -8 whereas a dim red dwarf might have an absolute magnitude of +16. The SunOur parent star. The structure of Sun's interior is the result of the hydrostatic equilibrium between gravity and the pressure of the gas. The interior consists of three shells: the core, radiative region, and convective region. Image source: http://eclipse99.nasa.gov/pages/SunActiv.html. The core is the hot, dense central region in which the 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.