K2-3

K2-3, also known as EPIC 201367065,[4] is a red dwarf with three known planets. All are Super-Earths, and the outermost is in the habitable zone.[8] It is on the borderline of being a late orange dwarf/K-type star, but because of its temperature, it is classified as a red dwarf (4,000 K is typically the division line between spectral class M and K).

K2-3
Observation data
Epoch J2000      Equinox J2000
Constellation Leo[1]
Right ascension 11h 29m 20.3918s[2]
Declination −01° 27′ 17.280″[2]
Apparent magnitude (V) 12.168±0.009[3]
Characteristics
Spectral type M0V[4]
B−V color index 1.35 ± 0.06[4]
Astrometry
Radial velocity (Rv)32.6±1[5] km/s
Proper motion (μ) RA: 94.034±0.094[2] mas/yr
Dec.: −78.139±0.057[2] mas/yr
Parallax (π)22.6610 ± 0.0553[2] mas
Distance143.9 ± 0.4 ly
(44.1 ± 0.1 pc)
Details
Mass0.601 ± 0.089[4] M☉
Radius0.561 ± 0.068[4] R☉
Temperature3835±70[6] K
Metallicity [Fe/H]−0.01±0.09[6] dex
Rotation40±2 d[7]
Age≥1[5] Gyr
Other designations
EPIC 201367065, 2MASS J11292037-0127173, WISE J112920.45-012718.0
Database references
SIMBADdata

At a distance of about 144 light-years,[2] the star ranks among the top 10 nearest stars known to have transiting planets. The star's proximity means it is bright enough to make it feasible for astronomers to study the planets' atmospheres to determine whether they are like Earth's atmosphere and possibly conducive to life.

Planetary system

K2-3 has at least three confirmed exoplanets:[5]

The K2-3 planetary system[4][6]
Companion
(in order from star)		 Mass Semimajor axis
(AU)		 Orbital period
(days)		 Eccentricity Inclination Radius
b 6.6±1.1 M⊕ 0.0777+0.0024
−0.0026		 10.05454±0.00003 0.06 ± 0.06 89.59+0.24
−0.40°		 2.29±0.23 R⊕
c 3.1+1.3
−1.2 M⊕		 0.1413+0.0044
−0.0047		 24.64638±0.00017 0.04 ± 0.04 89.70 ± 0.20° 1.77±0.18 R⊕
d 2.7+1.2
−0.8 M⊕		 0.2097+0.0065
−0.0070		 44.55764±0.00042 0.045 ± 0.045 89.79 ± 0.15° 1.65±0.17 R⊕

References
  1. Roman, Nancy G. (1987). "Identification of a Constellation From a Position". Publications of the Astronomical Society of the Pacific. 99 (617): 695–699. Bibcode:1987PASP...99..695R. doi:10.1086/132034. Vizier query form
  2. Brown, A. G. A.; et al. (Gaia collaboration) (August 2018). "Gaia Data Release 2: Summary of the contents and survey properties". Astronomy & Astrophysics. 616. A1. arXiv:1804.09365. Bibcode:2018A&A...616A...1G. doi:10.1051/0004-6361/201833051. Gaia DR2 record for this source at VizieR.
  3. Henden, A. A.; et al. (2016). "VizieR Online Data Catalog: AAVSO Photometric All Sky Survey (APASS) DR9 (Henden+, 2016)". VizieR On-line Data Catalog: II/336. Originally Published in: 2015AAS...22533616H. 2336. Bibcode:2016yCat.2336....0H.Vizier catalog entry
  4. "K2-3 PLANET HOST OVERVIEW PAGE". NASA Exoplanet Archive. Retrieved 2015-10-17.
  5. Crossfield, Ian J. M.; et al. (2015). "A Nearby M Star with Three Transiting Super-Earths Discovered by K2". The Astrophysical Journal. 804 (1). 10. arXiv:1501.03798. Bibcode:2015ApJ...804...10C. doi:10.1088/0004-637X/804/1/10.
  6. Damasso, M.; et al. (2018). "Eyes on K2-3: A system of three likely sub-Neptunes characterized with HARPS-N and HARPS". Astronomy and Astrophysics. 615. A69. arXiv:1802.08320. Bibcode:2018A&A...615A..69D. doi:10.1051/0004-6361/201732459. S2CID 58923147.
  7. Kosiarek, Molly R.; et al. (2019). "Bright Opportunities for Atmospheric Characterization of Small Planets: Masses and Radii of K2-3 b, c, and d and GJ3470 b from Radial Velocity Measurements and Spitzer Transits". The Astronomical Journal. 157 (3). 97. arXiv:1812.08241. Bibcode:2019AJ....157...97K. doi:10.3847/1538-3881/aaf79c.
  8. Three Super-Earths Found Circling Nearby Red Dwarf
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