Kepler-22
 A diagram of the Kepler-22b System, compared to our Inner Solar System. | |
| Observation data Epoch J2000 Equinox J2000 | |
|---|---|
| Constellation | Cygnus[1] |
| Right ascension | 19h 16m 52.2s |
| Declination | +47° 53′ 4.2″ |
| Apparent magnitude (V) | 11.664[2] |
| Characteristics | |
| Spectral type | G5[3] |
| Astrometry | |
| Distance | 620[3] ly (190 pc) |
| Details | |
| Mass | 0.970 ± 0.060[2] M☉ |
| Radius | 0.979 ± 0.020[2] R☉ |
| Luminosity | 0.79 ± 0.04[2] L☉ |
| Temperature | 5518 ± 44[2] K |
| Metallicity [Fe/H] | –0.29 ± 0.06[2] dex |
| Rotational velocity (v sin i) | 0.6 ± 1.0[2] km/s |
| Other designations | |
Kepler-22 is a star in the northern constellation of Cygnus, the swan, that is orbited by a planet found to be unequivocally within the star's habitable zone. It is located at the celestial coordinates: Right Ascension 19h 16m 52.2s, Declination +47° 53′ 4.2″.[4] With an apparent visual magnitude of 11.7,[2] this star is too faint to be seen with the naked eye. It can be viewed with a telescope having an aperture of at least 4 in (10 cm).[6] The estimated distance to Kepler-22 is 620 light-years (190 parsecs).[3]
Kepler-22 is slightly smaller and cooler than the Sun,[7] with a lower abundance of elements having more mass than helium.[2] It has a spectral type of G5, while the luminosity class remains undetermined.[3] This star is radiating 79%[2] of the Sun's luminosity from its outer atmosphere at an effective temperature of 5,518 K,[2] giving it the yellow-hued glow of a G-type star.[8] A projected rotational velocity of 0.6 km/s[2] suggests it has a low period of rotation.
Planetary system
On December 5, 2011, scientists from the Kepler mission announced that a possible Earthlike world (Kepler-22b) had been discovered orbiting in the star's habitable zone by NASA's Kepler spacecraft.[9] This was significant in that it was the first relatively Earth-sized extrasolar planet (about twice as big)[10] confirmed to be orbiting within a star's habitable zone.[11]
| Companion (in order from star) |
Mass | Semimajor axis (AU) |
Orbital period (days) |
Eccentricity | Inclination | Radius |
|---|---|---|---|---|---|---|
| b | < 0.11 MJ | 0.849 ± 0.018 | 289.8623 +0.016 −0.02 |
— | — | 2.4 R⊕ |
References
- ↑ "Cygnus – constellation boundary", The Constellations, International Astronomical Union, retrieved 2011-12-15
- ↑ 2.0 2.1 2.2 2.3 2.4 2.5 2.6 2.7 2.8 2.9 2.10 2.11 Kepler-22b, NASA Ames Research Center, retrieved 2011-12-06
- ↑ 3.0 3.1 3.2 3.3 3.4 Schneider, Jean, "Star: Kepler-22", Extrasolar Planets Encyclopaedia (Paris Observatory), retrieved 2011-12-06
- ↑ 4.0 4.1 "Kepler Discoveries". 2011-12-05.
- ↑ "GSC 03546-02301 -- Star", SIMBAD (Centre de Données astronomiques de Strasbourg), retrieved 2011-12-08
- ↑ Sherrod, P. Clay; Koed, Thomas L. (2003), A Complete Manual of Amateur Astronomy: Tools and Techniques for Astronomical Observations, Astronomy Series, Courier Dover Publications, p. 9, ISBN 0486428206
- ↑ "Kepler Confirms First Planet in Habitable Zone of Sun-Like Star". Universe Today. 2011-12-05.
- ↑ "The Colour of Stars", Australia Telescope, Outreach and Education (Commonwealth Scientific and Industrial Research Organisation), December 21, 2004, retrieved 2012-01-16
- ↑ Boyle, Rebecca (December 5, 2011). "Kepler Team Confirms First Earth-like planet in a habitable zone, And Finds 1,094 More Worlds". Popular Science. Retrieved December 5, 2011.
- ↑ Singhal, Nishant Kumar. "DIGG Kepler Team Confirms First Earth-like Planet in a Habitable Zone, And Finds 1,094 More Worlds". Popular Science. Retrieved 15 December 2011.
- ↑ "NASA Telescope Confirms Alien Planet in Habitable Zone". Space.com. 2011-12-05.
Coordinates: 
19h 16m 52.2s, +47° 53′ 4.2″
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