Kepler-442
A K-type star with a potentially habitable super-Earth.
Kepler-442, a K-type main-sequence star in Lyra, lies about 1,196 light-years away. It hosts a super-Earth, Kepler-442b, orbiting in the habitable zone. This discovery, along with those of Kepler-438 and Kepler-440, was announced in 2015 after the planet was detected by NASA's Kepler spacecraft.
Quick Facts
- Distance from earth
- approximately 1,196 light years
- Constellation
- Lyra
- Stellar type
- K-type main-sequence star
- Mass
- 61% of the Sun's mass
- Radius
- 60% of the Sun's radius
- Temperature
- 4402 K
- Age
- about 2.9 billion years
Facts from the source article.
Nomenclature and history
Before Kepler observations, the star was catalogued as 2MASS J19012797+3916482 in the 2MASS survey and as KIC 4138008 in the Kepler Input Catalog. When it showed signs of a transiting planet candidate, it received the Kepler object of interest number KOI-4742. The Kepler Mission detected planetary candidates by monitoring dips in stellar brightness, a method that can indicate orbiting planets but also other phenomena, so the term candidate was used. After the discovery paper was accepted, the Kepler team assigned the system the name Kepler-442, following the convention of numbering stars with confirmed planets in order of discovery. The sole detected planet candidate, with an orbital period of 112.3053 days, was designated Kepler-442b, the letter b indicating it was the first planet found around this star.
Stellar characteristics
Kepler-442 is a K-type main sequence star with about 61% of the Sun's mass and 60% of its radius. Its surface temperature is 4402 K, and its age is estimated at roughly 2.9 billion years, though the margin of error is large. The star has a metallicity of about –0.37, meaning it contains roughly 43% of the iron and heavier metals found in the Sun. Its luminosity is low, around 12% of the solar luminosity, and its apparent magnitude of 14.976 makes it invisible to the naked eye from Earth.
Planetary system
The only known planet, Kepler-442b, transits the star, allowing direct measurement of its period and relative diameter. It is a super-Earth with a radius 1.34 times that of Earth and orbits within the habitable zone. Its radius suggests it is likely a rocky planet, and it lies just outside the distance where tidal forces from the star would tidally lock it.
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