This is a simple rendition of a generic Hertzsprung-Russel diagram showing the locations of the major stellar types. The Y-axis is the Absolute Magnitude. For a Sun-like star, its Absolute Magnitude is about +5.0 ( it's actually +4.7 in the visual band) and corresponds to a total energy output of 3.8 x 10^33 ergs/second. A star with an Absolute Magnitude of -5.0 has a 'luminosity' of 10^(-.4 x (-5.0 - 5.0) = 10^4.0 times that of the Sun or 3.8 x 10^37 ergs/sec which is typical of many supergiant stars. These stars are also 10-20 times the mass of the Sun and are destined to become supernovae after about 100 million years.

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