Stars

by Lisa Staires 4 months ago in space

Star Classifications & Types

Stars

Stars are classified by their spectra (elements they absorb) & their temperature. There are seven main star types in order of lowering temperatures starting with O, B, A, F, G, K, & M. O & B stars are very bright & uncommon, while M stars are dim but common.

O Stars are blue in color with approximate surface temperatures over 25,000. Their average mass is approximately 60 times bigger than our sun & an average radius 15 times bigger. Their luminosity is approximately 1,400,000 brighter than ours as well. Main characteristics are singly ionized helium lines (HI) either in emissions or absorption with strong UV. An example of an O classification star is 10 Lacertra.

B stars are also blue in color with approximate surface temperatures between 11,000 to 25,000. Their average mass is approximately 18 times bigger than our sun with an average approximate radius of 7 times bigger. Their luminosity is approximately 20,000 times brighter. Main characteristics are neutral helium lines (HII) in absorption. Examples of a B classification stars is Rigel & Spica.

A stars yes you guessed it is also blue in color with approximate temperatures between 7,500 to 11,000. Their average mass is approximately 3.2 times bigger than our sun with an average approximate radius of 2.5 times bigger. Their luminosity is approximately 80 times brighter. Main characteristics are hydrogen (H) lines for AO stars, decreasing for other A's. Examples of A classification stars is Sirius & Vega.

F stars are blue to white in color with approximate surface temperatures between 6,000 to 7,500. Their average mass is approximately 1.7 times bigger than our sun with an average approximate radius of 1.3 times bigger. Their luminosity is approximately 6 times brighter. Main characteristics are Ca II absorption, metallic lines become noticeable. Examples of F classification stars is Canopus & Procyon.

G stars are white to yellow in color with approximate surface temperatures between 5,000 to 6,000. Their average mass is approximately 1.1 times bigger than our sun with an average approximate radius of 1.1 times bigger. Their luminosity is approximately 1.2 times brighter. Main characteristics are absorption lines of metallic atoms & ions (e.g. once ionized calcium). Examples of G classification stars is Our Sun & Capella.

K stars are orange to red in color with approximate surface temperatures between 3,500 to 5,000. Their average mass is approximately 0.8 times smaller than our sun with an average radius of 0.9 times smaller. Their luminosity is approximately 0.4 times dimmer. Main characteristics are metallic lines and some blue continuum. Examples of K classification stars is Arcturus & Aldebaran.

M stars are red in color with approximate surface temperatures under 3,500. Their average mass is approximately 0.3 times smaller than our sun with an average radius of 0.4 times smaller. Their luminosity is approximately 0.04 times dimmer. Main characteristics are some molecular bands of titanium oxide. Examples of M classification stars is Bettelgeuse & Antares.

Dwarf Stars

Dwarf stars are relatively small stars up to 20 times bigger than our sun & up to 20,000 times brighter. Yellow dwarf stars are small, main sequence stars. A perfect example of a yellow dwarf star is our sun. Red dwarf stars are small, cool, & very faint main sequence stars whose surface temperature is approximately 4,000. Red dwarf stars are the most common type of star. An example of a red dwarf star is located in a neighboring solar system; its name is Proxima Centauri.

Giant & Super Giant Stars

Red giants are relatively old stars whose diameter is approximately 100 times bigger than its original size & are cooler with an approximate surface temperature under 6,500. They're frequently orange in color. Betelgeuse in the center of Orion's Belt constellation is a red giant. It is approximately 20 times bigger & approximately 14,000 times brighter than out sun. Blue giants are huge, very hot, blue stars. It is a main sequence star that burns helium. Rigel, the brightest star in the Orion's Belt constellation is an example of a blue giant. Super giant stars are the biggest known type of star; some almost as big as our entire solar system. These stars are rare. Examples of super giant stars are Antares & VX Sagittari. When super giant stars die they supernova & become black holes.

Faint, Virtually Dead Stars

White dwarf stars are small, very dense, & hot stars mostly made of carbon. These faint stars are what remains after a red giant star that lost its outer layers. Their nuclear cores are depleted making them roughly the size of Earth. They will eventually lose heat & become a cold, dark black dwarf. An example is Sirius B.

Brown dwarf stars whose mass is too small to have nuclear fusion occur at its core. A brown dwarf is not very luminous. An example Gliese 229 B. Neutron stars are very small, super dense which is composed mostly of tightly packed neutrons. It has a thin atmosphere of hydrogen, a diameter of approximately 5 to 10 miles & a density of roughly 10 to the 15th power gm/cm to the 3rd power. An example of a neutron star is Geminga. A pulsar is a rapidly spinning neutron star that emits energy in pulses. The best example is the Crab pulsar

Next I'll be typing about the different types of binary, trinary, quaternary, quintenary, sextenary, septenary & how unusual our very own sun is compared to them. Thanks for reading.

space
Lisa Staires
Lisa Staires
Read next: Understanding the Collective Intelligence of Pro-opinion
Lisa Staires
See all posts by Lisa Staires