A-Type Star

Sirius A+B
Image from Steve Bowers
Sirius A, A-type star, and its white dwarf companion

A hot white star near the brighter end of the sequence of spectral types. An A0 type star generally has a mass of about 3.2 to 3.5 times that of Sol, a luminosity of about 80 times, a surface temperature of about 9,900° Kelvin, and will spend about 440 million years on the main sequence. When it finally collapses, having exhausted all its fuel, it may form a black hole.

The A5 spectral type is about 20 times as luminous as Sol, with a surface temperature of about 8,500° Kelvin, and a mass of about twice that of Sol. These short-lived stars are distinguished by very strong hydrogen lines in A0 weakening towards A9, and ionized calcium increasing from A0 to A9. They have a large life-zone, but life, when found on suitable planets, is generally only of very primitive microbial type, not having time to evolve to higher forms. Like the O and B-type stars, A-types are valued by development corporations, amat farmers, and stellar engineers, dyson sphere builders, isolationist ai, and others who would like to capitalize on the huge energy output. Sirius is a well known A1-type star, and several star-husbandry projects are already underway there.

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Development Notes
Text by M. Alan Kazlev
Initially published on 31 December 2001.