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A Class G star is the third-dimmest type of main sequence star beside brown dwarfs. They are typically colored yellow or yellow-white. They made up roughly 8% of all main-sequence stars.

A typical Class G star has a mass of 0.9 (0.8 to 1.04) solar masses, a radius of 1.05 (0.96 to 1.15) solar radii, a luminosity of 1 (0.6 to 1.5) solar luminosity, a surface temperature of 5,600 K (5,200 K to 6,000 K), and a lifespan of 10,000,000,000 years on average. The core of Class G stars are usually at the range of 15,000,000°K (25,000,000°F).

Their habitable zones range from ~0.7 to 1.1 AU, and their long lifespans and relatively high brightness mean they are good candidates for life-bearing planets. Earth's sun is a class G star, actually, as are many stars with known extrasolar planets.

In the search for extraterrestial life, these stars, especially the less bright G stars (<G5V) have planets that are possible candidates for alien life. While they are good candidates, these stars are overlooked by K-class stars.

Life Cycle

  • 0B yrs: Random protostar's gas forms a moderate-sized yellow star.
  • 1B yrs: A newborn yellow dwarf star finally formed.
  • 1.5B years: Star's planets, if any, finalized.
  • 2B years: Star's system established.
  • 5B years: Peak of well-being of star
  • 6.5B years: Star is increasingly luminous.
  • 9.5B years: Star Becomes an orange subgiant.
  • 10B years: Star becomes a red giant.
  • 10.5B years: Star explodes into a planetary nebula and leaves behind a white dwarf
  • 11B years: Planetary nebula evaporates.
  • 12B years: The white dwarf's peak in luminosity, before a slow cooldown.
  • 15B years: White dwarf is considerably cooler, although it still has extremities.

Properties

Properties of typical G-type main-sequence stars
Spectral type Mass Radius Luminosity Temperature (Fahrenheit)
G0V 1.07 1.12 1.35 10,214
G1V 1.03 1.06 1.20 10,088
G2V 1.00 1.01 1.02 9,926
G3V 0.99 0.994 0.98 9,836
G4V 0.985 0.986 0.91 9,764
G5V 0.98 0.982 0.89 9,728
G6V 0.97 0.949 0.79 9,620
G7V 0.95 0.939 0.74 9,530
G8V 0.94 0.909 0.68 9,404
G9V 0.9 0.876 0.55 9,224

See Also

Stellar Classes
Φ · Ψ · Ω · Q · DE · GR · σ ς · Θ · N · D · BS · Y · T · L · M · C · S · QS · K · G · F · A · B · LBV · β · O · W · N · X · n0 · Exotic (Π · Σ · Γ · Δ · μ) · δ · I · TŻO · BL · ·
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