Main Sequence

After formation, star masses correlate with other star properties {Main Sequence}. Main-Sequence stars have mass and brightness that depend on surface temperature, which determines color. 98% of stars are on Main Sequence.

types

Giant blue stars are 30,000 K at surface, have masses 60 times Sun mass, last 10^8 years, are in class O, and have strongly ionized gases.

Blue-white stars are 20,000 K at surface, last 10^8 years, are in class B, have much neutral helium, and are 10% of stars.

White stars are 11,000 K at surface, are in class A, and are predominantly hydrogen.

Yellow-white stars are 7800 K at surface, are in class F, and have hydrogen decreasing and metals increasing.

Yellow stars are 6700 K at surface, are in class G, and have metals predominant.

Yellow-orange stars are 5600 K at surface and last 10^10 years.

Orange stars are 4500 K at surface, are in class K, and metals surpass hydrogen.

Red stars are 3400 K at surface, are 0.1 Sun mass, last 10^11 years, are in class M, have titanium oxide, and have weak violet light.

1% of stars are fainter than class M stars: class W, class R, class N, and class S.

lifetimes

Large stars live shorter, because they burn faster.

rotation

Main-Sequence stars rotate every 4 hours to 30 days. Bigger stars spin faster.

evolution

Over time, Main-Sequence stars increase diameter by 30% and double brightness, but surface temperature and mass stay constant. Stars accumulate helium at center, as nuclear fusion turns hydrogen into helium.

large stars

Large stars can be 40 to 120 times more massive than Sun, such as Pistol Star and LBV 1806-20. Stars cannot be larger, because higher temperature blows gases away faster.

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