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Star Classification: Difference between revisions
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==Spectral Types== | ==Spectral Types== | ||
There are seven major spectral types of stars, forming a continuous band of types from | There are seven major spectral types of stars, forming a continuous band of types from O through M: | ||
O B A F G K M | |||
These are divided into ten numbered subtypes. For example: | These are divided into ten numbered subtypes. For example, a star of spectral class "A" could be any one of the following: | ||
A0 A1 A2 A3 A4 A5 A6 A7 A8 A9 | A0 A1 A2 A3 A4 A5 A6 A7 A8 A9 | ||
Stars at the ' | Stars at the 'O' end of this band are hotter (around 50,000 degrees K); bluer in colour and more massive; those at the other end are cooler (around 2,000 degrees K), redder in colour and less massive. A conventional code for star colour is: | ||
* | * O - Violet = White | ||
* B - Blue = White | * B - Blue = White | ||
* A - White | * A - White | ||
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While a 'Giant' star may have a radius of up to 1,000 times that of Sol and be up to 100,000 times as luminous, most of the stars are in the 'main sequence' portion of their lifetimes and have values near the typical main sequence ones for their type. Sol, Earth's sun, is a type G. Its spectrum, as filtered by Earth's atmosphere, is the basis for standard illumination in Human quarters. | While a 'Giant' star may have a radius of up to 1,000 times that of Sol and be up to 100,000 times as luminous, most of the stars are in the 'main sequence' portion of their lifetimes and have values near the typical main sequence ones for their type. Sol, Earth's sun, is a type G. Its spectrum, as filtered by Earth's atmosphere, is the basis for standard illumination in Human quarters. | ||
===Type | ===Type O : (Violet-White)=== | ||
Main Sequence Value Ranges: (Approximate) | Main Sequence Value Ranges: (Approximate) | ||
* '''Temperature''': | * '''Temperature''': 28,000 - 50,000ºK | ||
* '''Mass''': 10 - 30 Solar Masses | * '''Mass''': 10 - 30 Solar Masses | ||
* '''Radius''': 2.5 - 3.0 Solar Radii | * '''Radius''': 2.5 - 3.0 Solar Radii | ||
* '''Luminosity''': 1,000 - 100,000 SOL | * '''Luminosity''': 1,000 - 100,000 SOL | ||
* '''Composition''': Ionized atoms, esp. Helium | |||
* '''Example''': Mintaka (O1-3 III) | |||
=== Type B: (Blue-White)=== | === Type B: (Blue-White)=== | ||
Main Sequence Value Ranges: (Approximate) | Main Sequence Value Ranges: (Approximate) | ||
* '''Temperature''': 10,000 - | * '''Temperature''': 10,000 - 28,000ºK | ||
* '''Mass''': 3-5 Solar Masses | * '''Mass''': 3-5 Solar Masses | ||
* '''Radius''': 2.0 - 3.5 Solar Radii | * '''Radius''': 2.0 - 3.5 Solar Radii | ||
* '''Luminosity''': 10 - 1,000 SOL | * '''Luminosity''': 10 - 1,000 SOL | ||
* '''Composition''': Natural Helium, some Hydrogen | |||
* '''Example''': Alpha Eridani A (B3 V-IV) | |||
===Type A: (White)=== | ===Type A: (White)=== | ||
Main Sequence Value Ranges: (Approximate) | Main Sequence Value Ranges: (Approximate) | ||
* '''Temperature''': 7,500 - 10, | * '''Temperature''': 7,500 - 10,000ºK | ||
* '''Mass''': 2 - 3 Solar Masses | * '''Mass''': 2 - 3 Solar Masses | ||
* '''Radius''': 1.5 - 2.0 Solar Radii | * '''Radius''': 1.5 - 2.0 Solar Radii | ||
* '''Luminosity''': 5 - 10 SOL | * '''Luminosity''': 5 - 10 SOL | ||
* '''Composition''': Strong Hydrogen, some ionized metals | |||
* '''Example''': Sirius A (A0-1 V) | |||
===Type F: (Yellow - White)=== | ===Type F: (Yellow - White)=== | ||
Main Sequence Value Ranges: (Approximate) | Main Sequence Value Ranges: (Approximate) | ||
* '''Temperature''': 6,000 - 7, | * '''Temperature''': 6,000 - 7,500ºK | ||
* '''Mass''': 1 - 2 Solar Masses | * '''Mass''': 1 - 2 Solar Masses | ||
* '''Radius''': 1.0 - 1.5 Solar Radii | * '''Radius''': 1.0 - 1.5 Solar Radii | ||
* '''Luminosity''': 1 - 5 SOL | * '''Luminosity''': 1 - 5 SOL | ||
* '''Composition''': Hydrogen and ionized metals, calcium and iron | |||
* '''Example''': Procyon A (F5 V-IV) | |||
===Type G: (Yellow)=== | ===Type G: (Yellow)=== | ||
Main Sequence Value Ranges: (Approximate) | Main Sequence Value Ranges: (Approximate) | ||
* '''Temperature''': | * '''Temperature''': 5,000 - 6,000ºK | ||
* '''Mass''': 0.8 - 1 Solar Masses | * '''Mass''': 0.8 - 1 Solar Masses | ||
* '''Radius''': 0.8 - 1.0 Solar Radii | * '''Radius''': 0.8 - 1.0 Solar Radii | ||
* '''Luminosity''': 0.1 - 1 SOL | * '''Luminosity''': 0.1 - 1 SOL | ||
* '''Composition''': Ionized calcium, both neutral and ionized metals | |||
* '''Example''': Sol (G2 V) | |||
===Type K: (Orange)=== | ===Type K: (Orange)=== | ||
Main Sequence Value Ranges: (Approximate) | Main Sequence Value Ranges: (Approximate) | ||
* '''Temperature''': 3,500 - | * '''Temperature''': 3,500 - 5,000ºK | ||
* '''Mass''': 0.5 - 0.8 Solar Masses | * '''Mass''': 0.5 - 0.8 Solar Masses | ||
* '''Radius''': 0.5 - 0.8 Solar Radii | * '''Radius''': 0.5 - 0.8 Solar Radii | ||
* '''Luminosity''': 0.01 - 0.1 SOL | * '''Luminosity''': 0.01 - 0.1 SOL | ||
* '''Composition''': Neutral metals | |||
* '''Example''': Alpha Centauri B (K0-3 V) | |||
===Type M: (Red)=== | ===Type M: (Red)=== | ||
Main Sequence Value Ranges: (Approximate) | Main Sequence Value Ranges: (Approximate) | ||
* '''Temperature''': 2, | * '''Temperature''': 2,500 - 3,500ºK | ||
* '''Mass''': 0.02 - 0.5 Solar Masses | * '''Mass''': 0.02 - 0.5 Solar Masses | ||
* '''Radius''': 0.01 - 0.5 Solar Radii | * '''Radius''': 0.01 - 0.5 Solar Radii | ||
* '''Luminosity''': 0.00001 - 0.01 SOL | * '''Luminosity''': 0.00001 - 0.01 SOL | ||
* '''Composition''': Ionized atoms, especially helium | |||
* '''Example''': Wolf 359 (M5-8 V) | |||
''This article was supplied by Starwind RPG.'' | ''This article was supplied by Starwind RPG, with modifications by Geoffrey Mandel's "Star Trek Star Charts" atlas.'' | ||
[[Category:Science]] | [[Category:Science]] | ||
[[Category:Astronomy]] | [[Category:Astronomy]] | ||