K2-3

K2-3

Observation data Epoch J2000      Equinox J2000
Constellation	Leo[1]
Right ascension	11^h 29^m 20.39171^s[2]
Declination	−01° 27′ 17.2817″[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)	30.24±0.46[2] km/s
Proper motion (μ)	RA: 94.116 mas/yr[2] Dec.: −78.003 mas/yr[2]
Parallax (π)	22.7374 ± 0.0220 mas[2]
Distance	143.4 ± 0.1 ly (43.98 ± 0.04 pc)
Details[5]
Mass	0.549+0.029 −0.027 M☉
Radius	0.546+0.018 −0.016 R☉
Luminosity (bolometric)	0.0587+0.0018 −0.0019 L☉
Surface gravity (log g)	4.704+0.023 −0.026 cgs
Temperature	3844+61 −63 K
Metallicity [Fe/H]	−0.157+0.075 −0.080 dex
Rotation	40±2 d[6]
Age	6.9±4.7 Gyr
Other designations
Gaia DR3 3796690380302214272, EPIC 201367065, 2MASS J11292037-0127173, WISE J112920.45-012718.0[7]
Database references
SIMBAD	data

K2-3, also known as EPIC 201367065,^[4] is a red dwarf star with three known planets. 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).

At a distance of 143 light-years (44 parsecs),^[2] 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 three confirmed exoplanets, discovered in 2015.^[8] All are low-density super-Earths or sub-Neptunes, with the outermost orbiting near the inner edge of the habitable zone.^[9][5]

The K2-3 planetary system^[5]^[10]

Companion (in order from star)	Mass	Semimajor axis (AU)	Orbital period (days)	Eccentricity	Inclination	Radius
b	5.11+0.65 −0.64 M🜨	0.0778±0.0026	10.054626(0)	<0.094	89.588+0.12 −0.100°	2.078+0.076 −0.067 R🜨
c	2.68±0.85 M🜨	0.1414±0.0047	24.646582(39)	<0.095	89.905+0.066 −0.088°	1.582+0.057 −0.051 R🜨
d	<1.6 M🜨	0.2097±0.0070	44.556456(97)	<0.097	89.788+0.033 −0.029°	1.458+0.056 −0.051 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. 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. 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. Diamond-Lowe, Hannah; et al. (2022), "The K2-3 System Revisited: Testing Photoevaporation and Core-powered Mass Loss with Three Small Planets Spanning the Radius Valley", The Astronomical Journal, 164 (5): 172, arXiv:2207.12755, Bibcode:2022AJ....164..172D, doi:10.3847/1538-3881/ac7807, S2CID 251067119
6. 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. S2CID 119440420.
7. "K2-3". SIMBAD. Centre de données astronomiques de Strasbourg. Retrieved 2024-04-19.
8. 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.
9. Damasso, Mario; 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.
10. Bonomo, A. S.; Dumusque, X.; et al. (April 2023). "Cold Jupiters and improved masses in 38 Kepler and K2 small-planet systems from 3661 high-precision HARPS-N radial velocities. No excess of cold Jupiters in small-planet systems". Astronomy & Astrophysics. arXiv:2304.05773. doi:10.1051/0004-6361/202346211. S2CID 261556620.