K2-21

Last updated
K2-21
Observation data
Epoch J2000        Equinox J2000
Constellation Aquarius [1]
Right ascension 22h 41m 12.88625s [2]
Declination −14° 29′ 20.3492″ [2]
Apparent magnitude  (V)12.85 [3]
Characteristics
Evolutionary stage Main sequence [2]
Spectral type M0.0±0.5V [3]
Apparent magnitude  (B)14.14±0.06 [3]
Apparent magnitude  (V)12.85±0.02 [3]
Apparent magnitude  (G)12.268±0.003 [2]
Apparent magnitude  (J)10.251±0.021 [4]
Apparent magnitude  (H)9.633±0.022 [4]
Apparent magnitude  (K)9.417±0.020 [4]
Astrometry
Radial velocity (Rv)3.54±0.82 [2] km/s
Proper motion (μ)RA: 20.672 mas/yr [2]
Dec.: -78.914 mas/yr [2]
Parallax (π)11.9662±0.0150  mas [2]
Distance 272.6 ± 0.3  ly
(83.6 ± 0.1  pc)
Details [3]
Mass 0.64±0.11  M☉
Radius 0.60±0.10  R☉
Luminosity (bolometric)0.086±0.064  L☉
Temperature 4043±375  K
Metallicity [Fe/H]−0.11±0.13  dex
Age >1  Gyr
Other designations
K2-21, EPIC 206011691, TIC 240766850, 2MASS J22411288-1429202 [4]
Database references
SIMBAD data
Exoplanet Archive data

K2-21, also known as EPIC 206011691, is a red dwarf star located 273 light-years (84 parsecs ) away in the constellation Aquarius. It hosts two known exoplanets, discovered in 2015 by the transit method as part of Kepler's K2 mission. [3] Both planets have significantly lower densities than Earth, indicating that they are not rocky planets and are better described as mini-Neptunes. The inner planet, K2-21b, is less dense than the outer planet, K2-21c. [5]

The K2-21 planetary system [5]
Companion
(in order from star)		 Mass Semimajor axis
(AU)		 Orbital period
(days)		 Eccentricity Inclination Radius
b1.59+0.52
−0.44  M🜨 		0.0731+0.0057
−0.0067 [3] 		9.3238+0.0002
−0.0001		—88.54+0.49
−0.59 ° 		1.93±0.07  R🜨
c3.88+1.22
−1.07  M🜨 		0.1026+0.0079
−0.0094 [3] 		15.5017±0.0002—89.02+0.33
−0.41 ° 		2.25±0.05  R🜨

References

  1. ↑ Roman, Nancy G. (1987). "Identification of a constellation from a position". Publications of the Astronomical Society of the Pacific . 99 (617): 695. Bibcode:1987PASP...99..695R. doi: 10.1086/132034 . Constellation record for this object at VizieR.
  2. 1 2 3 4 5 6 7 8 Vallenari, A.; et al. (Gaia collaboration) (2023). "Gaia Data Release 3. Summary of the content and survey properties". Astronomy and Astrophysics. 674: A1. arXiv: 2208.00211 . Bibcode:2023A&A...674A...1G. doi: 10.1051/0004-6361/202243940 . S2CID   244398875. Gaia DR3 record for this source at VizieR.
  3. 1 2 3 4 5 6 7 8 Petigura, Erik A.; et al. (2015). "Two Transiting Earth-Size Planets Near Resonance Orbiting a Nearby Cool Star". The Astrophysical Journal. 811 (2) 102. arXiv: 1507.08256 . Bibcode: 2015ApJ...811..102P . doi: 10.1088/0004-637X/811/2/102 .
  4. 1 2 3 4 "K2-21". SIMBAD . Centre de données astronomiques de Strasbourg . Retrieved 24 May 2023.
  5. 1 2 El Moutamid, Maryame; et al. (April 2023). "Mass derivation of planets K2-21b and K2-21c from transit timing variations". Monthly Notices of the Royal Astronomical Society. 520 (3): 4226–4234. arXiv: 2305.11359 . Bibcode: 2023MNRAS.520.4226E . doi: 10.1093/mnras/stad238 .


This page is based on this Wikipedia article
Text is available under the CC BY-SA 4.0 license; additional terms may apply.
Images, videos and audio are available under their respective licenses.