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Kepler-22b

Kepler-22b
Exoplanet List of exoplanets
Kepler-22b System Diagram.jpg
A diagram of the orbit of Kepler-22b within the Kepler-22 system, as compared to the inner Solar System, and their respective projected habitable zones.
Parent star
Star Kepler-22
Constellation Cygnus
Right ascension (α) 19h 16m 52.2s
Declination (δ) +47° 53′ 4.0″
Apparent magnitude (mV) 11.5 (B-band)
Distance 620 ly
(190 pc)
Spectral type G5V
Mass (m) 0.97 M
Radius (r) 0.979 ± 0.02 R
Temperature (T) 5518 ± 44 K
Age ~4 Gyr
Physical characteristics
Mass (m) <52.8 M
Radius (r) 2.04 +0.09
−0.07
R
Stellar flux (F) 1.137+0.146
−0.087
Temperature (T) 295 K (22 °C; 71 °F)
Orbital elements
Semi-major axis (a) 0.849 ± 0.018AU
(127 Gm)
Eccentricity (e) 0
Orbital period (P) 289.862 ± 0.02d
Inclination (i) 89.764 +0.042
−0.025
°
Discovery information
Discovery date 5 December 2011 (announced)
Discoverer(s) Kepler Science Team
Discovery method Transit
Discovery site Kepler telescope
Discovery status Published
Other designations
KOI-087.01, KOI-087 b, KIC-10593626 b, 2MASS J19165219+4753040 b
Database references
Extrasolar Planets
Encyclopaedia
data
SIMBAD data
Exoplanet Archive data
Open Exoplanet Catalogue data

Kepler-22b, also known by its Kepler object of interest designation KOI-087.01, is an extrasolar planet orbiting within the empirical habitable zone of the Sun-like star Kepler-22. It is located about 600 light-years (180 pc) from Earth in the constellation of Cygnus. It was discovered by NASA's Kepler Space Telescope in December 2011 and was the first known transiting planet to orbit within the habitable zone of a Sun-like star. Kepler-22 is too dim to be seen with the naked eye.

Kepler-22b's size is roughly twice that of Earth. Its mass and surface composition are unknown. An Earth-like composition for the planet has been ruled out. It is likely to have a volatile-rich composition with a liquid or gaseous outer shell. The only parameters of the planet's orbit that are currently available are its orbital period, which is about 290 days, and its inclination, which is approximately 90°. Evidence suggests that the planet has a moderate surface temperature, assuming that the surface is not subject to extreme greenhouse heating. In the absence of an atmosphere, its equilibrium temperature (assuming an Earth-like albedo) would be approximately 262 K (−11 °C).

The planet's first transit was observed on 12 May 2009. Confirmation of the existence of Kepler-22b was announced on 5 December 2011.


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