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A Class K star is the second-dimmest type of main sequence star besides brown dwarfs. They are typically colored yellow-orange or orange. They make up roughly 12% of all main-sequence stars.

A typical Class K star has a mass of 0.6 (0.45 to 0.8) solar masses, a radius of 0.8 (0.7 to 0.96) solar radii, a luminosity of 0.3 (0.08 to 0.6) solar luminosities, a surface temperature of 4,450 K (3,700 K to 5,200 K), and a lifespan of 50 to 100 billion years. K-type stars' cores usually have temperatures of 11,000,000°K (20,000,000°F).

With their extremely long lifespans and acceptable brightness, it is very likely that many Class K stars have life-bearing planets, and many exoplanets have been discovered around stars of this class. They live from 30,000,000 to 100,000,000,000 years, 50,000,000,000 years on average, thus there are no dying K stars.

On the search for extraterrestial life, these types of stars are of particular interest, due to their long lives, lower rates of ultraviolet radiation, approvable habitable zones, their frequency, and their planets. One conflict can be their planets' shorter years of an average of 180 days, but, overall, orange stars' planets seem to be good candidates for alien life.

Life Cycle

  • 0B yrs: Random protostar's gas forms a moderately small orange star.
  • 1B yrs: A newborn orange dwarf star finally formed.
  • 5B years: Star's planets, if any, finalized
  • 10B years: Star's system established.
  • 25B years: Peak of well-being of star
  • 40B years: Star is increasingly luminous.
  • 50B years: Star Becomes an orange subgiant.
  • 51B years: Star becomes a red subgiant.
  • 52B years: Star explodes into a planetary nebula and leaves behind a white dwarf
  • 53B years: Planetary nebula evaporates.
  • 55B years: The white dwarf's peak in luminosity, before a slow cooldown.
  • 60B years: White dwarf is considerably cooler, although it still has extremities.

Properties

Properties of typical K-type main-sequence stars
Spectral type Mass Radius Luminosity Temperature (Fahrenheit)
K0V 0.88 0.817 0.46 9,026
K1V 0.86 0.814 0.41 8,846
K2V 0.82 0.763 0.37 8,720
K3V 0.78 0.729 0.28 8,234
K4V 0.73 0.726 0.20 7,820
K5V 0.70 0.698 0.17 7,532
K6V 0.69 0.661 0.14 7,280
K7V 0.64 0.654 0.10 6,920
K8V 0.62 0.587 0.087 6,722
K9V 0.59 0.552 0.079 6,614

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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