K2-72: Difference between revisions
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| class= M2V<ref name=apj698_1_519>{{Cite journal | last1=Kaltenegger | first1=Lisa | last2=Traub | first2=Wesley A. | title=Transits of Earth-like Planets | journal=The Astrophysical Journal | volume=698 | issue=1 | pages=519–527 |date=June 2009 | doi=10.1088/0004-637X/698/1/519 | bibcode=2009ApJ...698..519K |arxiv = 0903.3371 }} See red dwarf characteristics table near bottom of paper. The temperature of K2-72 is 3497 K, which is consistent with an M2V class red dwarf star.</ref> |
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Revision as of 00:02, 19 July 2016
| Observation data Epoch J2000 Equinox J2000 | |
|---|---|
| Constellation | Aquarius |
| Right ascension | 22h 18m 29.27s[1] |
| Declination | −09° 36′ 44.6″[1] |
| Characteristics | |
| Spectral type | M2V[2] |
| Astrometry | |
| Distance | 181[3] ly (55[3] pc) |
| Details | |
| Mass | 0.217 ± 0.081[1] M☉ |
| Radius | 0.232 ± 0.56[1] R☉ |
| Surface gravity (log g) | 5.048±0.075[1] cgs |
| Temperature | 3497 ± 150[1] K |
| Other designations | |
EPIC 206209135, 2MASS J22182923-0936444 | |
| Database references | |
K2-72 is a cool red dwarf star located about 181 light-years (55 pc) away from the Earth in the constellation of Aquarius. It is known to host four planets, all smaller then Earth, with two of them residing within the habitable zone.
Nomenclature and history
Prior to Kepler observation, K2-72 had the 2MASS catalogue number 2MASS J22182923-0936444.
The star's planetary companions was discovered by NASA's Kepler Mission, a mission tasked with discovering planets in transit around their stars. The transit method that Kepler uses involves detecting dips in brightness in stars. These dips in brightness can be interpreted as planets whose orbits move in front of their stars from the perspective of Earth. The name K2-72 derives directly from the fact that the star is the catalogued 72nd star discovered by the K2 mission to have confirmed planets.
The designation b, c, d, and e derives from the order of discovery. The designation of b is given to the first planet orbiting a given star, and e to the last.[4] In the case of K2-72, there were planet, so only letters b to e are used.
Stellar characteristics
K2-72 is a M-type star that is approximately 21% the mass of and 23% the radius of the Sun. It has a surface temperature of 3497 K and its age is unknown. In comparison, the Sun is about 4.6 billion years old[5] and has a surface temperature of 5778 K.[6]
The star's apparent magnitude, or how bright it appears from Earth's perspective, is unknown.
Planetary system
The star is known to host four planets, with two orbiting in the habitable zone. All are smaller than Earth by some magnitude.
| Companion (in order from star) |
Mass | Semimajor axis (AU) |
Orbital period (days) |
Eccentricity | Inclination | Radius |
|---|---|---|---|---|---|---|
| b | — | 0.037 | 5.5774 | — | — | 0.75±0.20 R🜨 |
| d | — | 0.046 | 7.76 | — | — | 0.76±0.20 R🜨 |
| c | — | 0.0722 | 15.1871 | — | — | 0.86±0.22 R🜨 |
| e | — | 0.098 | 24.1669 | — | — | 0.82±0.22 R🜨 |
References
- ^ a b c d e f g "NASA Exoplanet Archive". NASA Exoplanet Science Institute. 18 July 2016. Retrieved 2016-07-18.
- ^ Kaltenegger, Lisa; Traub, Wesley A. (June 2009). "Transits of Earth-like Planets". The Astrophysical Journal. 698 (1): 519–527. arXiv:0903.3371. Bibcode:2009ApJ...698..519K. doi:10.1088/0004-637X/698/1/519. See red dwarf characteristics table near bottom of paper. The temperature of K2-72 is 3497 K, which is consistent with an M2V class red dwarf star.
- ^ a b http://www.nasa.gov/feature/ames/kepler/nasa-s-kepler-confirms-100-exoplanets-during-its-k2-mission
- ^ Hessman, F. V.; Dhillon, V. S.; Winget, D. E.; Schreiber, M. R.; Horne, K.; Marsh, T. R.; Guenther, E.; Schwope, A.; Heber, U. (2010). "On the naming convention used for multiple star systems and extrasolar planets". arXiv:1012.0707 [astro-ph.SR].
- ^ Fraser Cain (16 September 2008). "How Old is the Sun?". Universe Today. Retrieved 19 February 2011.
- ^ Fraser Cain (15 September 2008). "Temperature of the Sun". Universe Today. Retrieved 19 February 2011.
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