Kepler-442b

Kepler-442b[1][2][3]
Exoplanet List of exoplanets

Approximate size comparison of Kepler-442b (left) with Earth.
Parent star
Star Kepler-442
Constellation Lyra[2]
Right ascension (α) 19h 01m 27.98s
Declination (δ) +39° 16′ 48.30″
Apparent magnitude (mV) 14.976[3]
Distance1120; 1100[2] ly
(342+19
−22[3] pc)
Mass (m) 0.609+0.00
−0.024[3] M☉
Radius (r) 0.598+0.023
−0.024[3] R☉
Temperature (T) 4402 ± 100[3] K
Metallicity [Fe/H] -0.370 ± 0.10[3]
Age 2.9+8.1
−0.2[3] Gyr
Physical characteristics
Mass(m)2.3+5.9
−1.3[4] M⊕
Radius(r)1.34+0.11
−0.18[3] R⊕
Stellar flux(F⊙)0.66+0.23
−0.41[3] ⊕
Temperature (T) 233 K (−40 °C; −40 °F)[4]
Orbital elements
Semi-major axis(a) 0.409+0.209
−0.060[3] AU
Eccentricity (e) 0.04+0.08
−0.04[3]
Orbital period(P) 112.3053+0.024
−0.0028[3] d
Inclination (i) 89.94+0.06
−0.12[3]°
Discovery information
Discovery date 2015[3][5]
Discoverer(s)
Discovery method Transit
Discovery site Kepler Space Observatory
Discovery status To be published in refereed article
Other designations
KOI-4742.01; Kepler-442 b; KOI-4742 b; K04742.01; WISE J190127.98+391648.2 b; KIC 4138008 b; 2MASS J19012797+3916482 b
Database references
Extrasolar Planets
Encyclopaedia		data
SIMBADdata
Exoplanet Archivedata
Open Exoplanet Cataloguedata

Kepler-442b (also known by its Kepler Object of Interest designation KOI-4742.01) is a confirmed near-Earth-sized exoplanet, likely rocky, orbiting within the habitable zone of the K-type star[6] Kepler-442, about 1,120 light-years (342 pc) from Earth in the constellation Lyra.[1][2] The planet was discovered by NASA's Kepler spacecraft using the transit method, in which the dimming effect that a planet causes as it crosses in front of its star is measured. NASA announced the confirmation of the exoplanet on 6 January 2015.[1]

Features

Host star

The star Kepler-442 is a K-type main-sequence star with a mass of 0.61 solar masses, a radius of 0.59 solar radii and surface temperature of 4129 °C. Its metallicity, estimated at −0.37, is lower than that of the Sun, indicating a relative lack of heavy elements.[7] K-type main-sequence stars are smaller than the Sun and live longer, remaining on the main sequence 15 to 30 billion years compared to the Sun's estimated 10 billion.[8] Despite these properties, the small M-type and K-type stars can pose a threat to life.[9] Because of their high stellar activity at the beginning of their lives, they emit strong solar winds. The duration of this period is inversely linked to the size of the star.[10] Kepler-442b orbits a K-type star 0.2 AU outside of the zone where gravitational tug would be strong enough to tidally lock it.[11]

The age of the star system is unknown, But most estimates vary from 2.7 billion years and 8.1 billion years.[12] For comparison, the Solar System is 4.5 billion years old.

Confirmed exoplanet

Kepler-442b is a near-Earth-sized exoplanet with a radius 1.34 times that of Earth. The planet orbits the K-type star[6] Kepler-442 once every 112.3 days.[1][2] It is estimated to have a mass of 2.34 Earth masses.[11] The surface gravity on Kepler-442b would be only 30% stronger than that of Earth, assuming a rocky composition similar to that of Earth.[13] This would be a tolerable difference to humans.

Potential habitability

The planet was announced as being located within the habitable zone of Kepler-442, a region where liquid water could exist on the surface of the planet. It was described as being one of the most Earth-like planets, in terms of size and temperature, yet found.[1][2]

Notable Exoplanets – Kepler Space Telescope
Confirmed small exoplanets in habitable zones.
(Kepler-62e, Kepler-62f, Kepler-186f, Kepler-296e, Kepler-296f, Kepler-438b, Kepler-440b, Kepler-442b)
(Kepler Space Telescope; 6 January 2015).[1]

See also

References

  1. 1 2 3 4 5 6 Clavin, Whitney; Chou, Felicia; Johnson, Michele (6 January 2015). "NASA's Kepler Marks 1,000th Exoplanet Discovery, Uncovers More Small Worlds in Habitable Zones". NASA. Retrieved 6 January 2015.
  2. 1 2 3 4 5 6 Sample, Ian (7 January 2015). "Kepler 438b: Most Earth-like planet ever discovered could be home for alien life". The Guardian. Retrieved 7 January 2015.
  3. 1 2 3 4 5 6 7 8 9 10 11 12 13 14 15 Torres, Guillermo; Kipping, David M.; Fressin, Francois; Caldwell, Douglas A.; Twicken, Joseph D.; Ballard, Sarah; Batalha, Natalie M.; Bryson, Stephen T.; Ciardi, David R.; Henze, Christopher E.; Howell, Steve B.; Isaacson, Howard T.; Jenkins, Jon M.; Muirhead, Philip S.; Newton, Elisabeth R.; Petigura, Erik A.; Barclay, Thomas; Borucki, William J.; Crepp, Justin R.; Everett, Mark E.; Horch, Elliott P.; Howard, Andrew W.; Kolbl, Rea; Marcy, Geoffrey W.; McCauliff, Sean; Quintana, Elisa V. (2015). "Validation of Twelve Small Kepler Transiting Planets in the Habitable Zone". arXiv:1501.01101 [astro-ph.EP].
  4. 1 2 "HEC: Data of Potential Habitable Worlds".
  5. ↑ Staff (2015). "Planet Kepler-442 b". The Extrasolar Planets Encyclopaedia. Retrieved 11 January 2015.
  6. 1 2 Gilster, Paul (6 January 2015). "AAS: 8 New Planets in Habitable Zone". Centauri-dreams.org. Retrieved 9 January 2015.
  7. ↑ "PHL's Exoplanets Catalog - Planetary Habitability Laboratory @ UPR Arecibo". Retrieved 4 October 2015.
  8. ↑ Fraser Cain (4 February 2009). "Star Main Sequence". Universe Today. Retrieved 4 October 2015.
  9. ↑ "Red Dwarf Stars May Be Best Chance for Habitable Alien Planets". Space.com. Retrieved 4 October 2015.
  10. ↑ "Can Life Thrive Around a Red Dwarf Star?". Space.com. Retrieved 4 October 2015.
  11. 1 2 "Planetary Habitability Laboratory at University of Puerto Rico".
  12. ↑ "Kepler-442 b". Retrieved 4 October 2015.
  13. ↑ Extrapolated from the information given in "HEC: Data of Potentially Habitable Worlds - Planetary Habitability Laboratory @ UPR Arecibo". phl.upr.edu. Retrieved 2015-09-15. Using a planetary composition similar to earth.

External links

Wikimedia Commons has media related to Kepler Mission.

Coordinates: 19h 01m 27.98s, +39° 16′ 48.30″

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