Kepler-186e
Discovery date | 17 April 2014 |
---|---|
Transit | |
Orbital characteristics | |
0.11–0.1216 AU | |
Eccentricity | <0.24 |
22.407704 d | |
Inclination | 88.24 |
Star | Kepler-186 |
Physical characteristics | |
Mean radius | 1.27±0.15 R🜨 |
Mass | ~2.29 ME |
Temperature | Teq: 323 K (50 °C; 122 °F) |
Kepler-186e (also known by its Kepler Object of Interest designation KOI-571.04) is a confirmed
Physical characteristics
Mass, orbit, and composition
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 0.39 AU for Mercury). 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
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 probably tidally 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 of habitability, which could support life.
Kepler-186e's axial 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
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
As the
See also
References
- ^ S2CID 1892595.
- ^ a b Johnson, Michele; Harrington, J.D. (17 April 2014). "NASA's Kepler Discovers First Earth-Size Planet In The 'Habitable Zone' of Another Star". NASA. Archived from the original on 17 April 2014.
- ^ S2CID 118709918.
- S2CID 119118620.
- ^ Glister, Paul (5 November 2013). "Earth-Sized Planets in Habitable Zone Common". Centauri Dreams. Archived from 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. Archived from the original on 20 August 2013.{{cite web}}
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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. Archived from 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. .