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Kepler-186e

Coordinates:Sky map19h54m36.651s,+43° 57′ 18.06″
From Wikipedia, the free encyclopedia

Kepler-186e[1][2]
Discovery
Discovery siteKepler Space Observatory
Discovery date17 April 2014
Transit
Orbital characteristics
0.11–0.1216AU
Eccentricity<0.24
22.407704d
Inclination88.24
StarKepler-186
Physical characteristics
1.27±0.15R🜨
Mass~2.29ME
TemperatureTeq:323 K (50 °C; 122 °F)

Kepler-186e(also known by its Kepler Object of Interest designationKOI-571.04) is a confirmedexoplanetorbiting thered dwarfstarKepler-186,approximately 582light yearsaway from Earth in theconstellationofCygnus.It is near the optimistic habitable zone but probably not in it, possibly making it have arunaway greenhouse effect,likeVenus.The exoplanet was found by using thetransit method,in which the dimming effect that a planet causes as it crosses in front of its star is measured. Four additional planets orbiting the star (all modestly larger than Earth) were also discovered.

Physical characteristics

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Mass, orbit, and composition

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The exoplanet is only slightly larger than Earth, with a radius 1.27–1.33 times that of Earth. Its mass is not known but it is likely to have a similar composition to Earth, giving it a mass of about 2.29–2.72 times the mass of the Earth. Kepler-186e orbits an M-dwarf star with about 4% of the Sun's luminosity with an orbital period of 22.4077 days and an orbital radius of about 0.11 times that of Earth's (compared to 0.39AUforMercury). The habitable zone for this system is estimated conservatively to extend over distances receiving from 88% to 25% of Earth's illumination (from 0.22 to 0.40 AU).[1]

Formation, tidal evolution and habitability

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The star hosts four other planets discovered so far. Because of the very slow evolution of red dwarfs, the age of the Kepler-186 system is poorly constrained, although it is likely to be greater than a few billion years.[3]Due to its proximity to its star, Kepler-186e is probablytidally locked,facing one side to its star at all times, and one side facing away from its star at all times. The side in permanent daylight would be extremely hot and the side in permanent darkness would be extremely cold. But between these hostile environments, there would be a sliver ofhabitability,which could support life.

Kepler-186e'saxial tilt(obliquity) is likely very small. Its orbit is probably close to circular, so it will lack seasonal changes. However, the axial tilt could be larger (about 23 degrees) if another undetected nontransiting planet orbits between it and Kepler-186f; planetary formation simulations have shown that the presence of at least one additional planet in this region is likely. If such a planet exists, it cannot be much more massive than Earth as it would then cause orbital instabilities.[3]

Discovery

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The exoplanet, along with the other planets of the Kepler-186 system (including 186f), were announced on April 17, 2014, in an article published by NASA.[2]

Previous names

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As theKepler telescopeobservational campaign proceeded, an initially identified system was entered in theKepler Input Catalog(KIC), and then progressed as a candidate host of planets to aKepler Object of Interest(KOI). Thus,Kepler-186started asKIC 8120608and then was identified asKOI 571.[4]Kepler-186e was mentioned when known as KOI-571-04 or KOI-571.04 or using similar nomenclatures in 2013 in various discussions and publications before its full confirmation.[5]

See also

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References

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  1. ^abQuintana, E. V.;Barclay, T.; Raymond, S. N.; Rowe, J. F.; Bolmont, E.; Caldwell, D. A.; Howell, S. B.; Kane, S. R.; Huber, D.; Crepp, J. R.;Lissauer, J. J.;Ciardi, D. R.; Coughlin, J. L.; Everett, M. E.; Henze, C. E.; Horch, E.; Isaacson, H.; Ford, E. B.; Adams, F. C.; Still, M.; Hunter, R. C.; Quarles, B.; Selsis, F. (18 April 2014)."An Earth-Sized Planet in the Habitable Zone of a Cool Star"(PDF).Science.344(6181): 277–280.arXiv:1404.5667.Bibcode:2014Sci...344..277Q.doi:10.1126/science.1249403.PMID24744370.S2CID1892595.
  2. ^abJohnson, Michele; Harrington, J.D. (17 April 2014)."NASA's Kepler Discovers First Earth-Size Planet In The 'Habitable Zone' of Another Star".NASA.Archivedfrom the original on 17 April 2014.
  3. ^abBolmont, Emeline; Raymond, Sean N.; von Paris, Philip; Selsis, Franck; Hersant, Franck; Quintana, Elisa V.; Barclay, Thomas (16 April 2014). "Formation, tidal evolution and habitability of the Kepler-186 system".The Astrophysical Journal.1404(1): 4368.arXiv:1404.4368.Bibcode:2014ApJ...793....3B.doi:10.1088/0004-637X/793/1/3.S2CID118709918.
  4. ^Rowe, Jason F.; Marcy, Geoffrey W.; Lissauer, Jack J.; Jontof-Hutter, Daniel; Mullally, Fergal; Gilliland, Ronald L.; Issacson, Howard; Ford, Eric; Howell, Steve B.; Borucki, William J.; Haas, Michael; Huber, Daniel; Steffen, Jason H.; Thompson, Susan E.; Quintana, Elisa; Barclay, Thomas; Still, Martin; Fortney, Jonathan; Gautier, T. N.; Hunter, Roger; Caldwell, Douglas A.; Ciardi, David R.; Devore, Edna; Cochran, William; Jenkins, Jon; Agol, Eric; Carter, Joshua A.; Geary, John (27 February 2014). "Validation of Kepler's Multiple Planet Candidates. III: Light Curve Analysis & Announcement of Hundreds of New Multi-planet Systems".The Astrophysical Journal.784(1): 45.arXiv:1402.6534.Bibcode:2014ApJ...784...45R.doi:10.1088/0004-637X/784/1/45.S2CID119118620.
  5. ^Glister, Paul (5 November 2013)."Earth-Sized Planets in Habitable Zone Common".Centauri Dreams.Archivedfrom the original on 19 April 2014.See comment by "Holger 16 November 2013 at 14:21".
    ^redakce [ "editor" ] (6 August 2013)."Kepler (asi) našel obyvatelnou planetu o velikosti Země"[Kepler (probably) found a habitable planet the size of Earth] (in Czech). exoplanety.cz.Archivedfrom the original on 20 August 2013.{{cite web}}:|author=has generic name (help)
    ^"Kepler: Erster Kandidat einer habitablen Exoerde Veröffentlicht"[Kepler: First candidate of a habitable Exoplanet Published].Zauber der Sterne [Magic of the stars](in German). 19 August 2013.Archivedfrom the original on 27 September 2013.
    ^Bovaird, Timothy; Lineweaver, Charles H. (1 August 2013)."Exoplanet Predictions Based on the Generalised Titius-Bode Relation".Monthly Notices of the Royal Astronomical Society.435(2): 14–15.arXiv:1304.3341.Bibcode:2013MNRAS.435.1126B.doi:10.1093/mnras/stt1357.

Notes

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