BY LETTER
A-Type Star
 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.
Related Articles
- Apparent Brightness of the Local Sun
- B-Type Star
- F-type Star
- G-Type Star
- K-type Star
- M-Type Star
- O-type Star
- Sirius
- Spectral Class - Text by M. Alan Kazlev
A class to which a star belongs because of its spectrum, which in turn is determined by its temperature. The spectral classes are O, B, A, F, G, K, and M, from hottest to coolest.
Appears in Topics
Development Notes
Text by M. Alan Kazlev
Initially published on 31 December 2001.
Initially published on 31 December 2001.
