K2-187

K2-187, also known as EPIC 212157262, is a Sun-like star in K2 Campaign 5. It is very close in size and temperature to the Sun, and has a system of four confirmed exoplanets ranging between 1.4 R_🜨 and 3.2 R_🜨. The innermost planet takes just 18 hours to orbit its star, while the outermost planet orbits every 2 weeks.^[6]

K2-187

Observation data Epoch J2000      Equinox J2000
Constellation	Cancer[1]
Right ascension	08h 50m 05.668s[2]
Declination	+23° 11′ 33.36″[2]
Apparent magnitude (V)	13.081[3]
Characteristics
Evolutionary stage	main sequence[2]
Spectral type	G7[4]
Astrometry
Proper motion (μ)	RA: −11.872[2] mas/yr Dec.: −30.597[2] mas/yr
Parallax (π)	3.0740±0.0192 mas[2]
Distance	1,061 ± 7 ly (325 ± 2 pc)
Details
Mass	0.967+0.025 −0.024[5] M☉
Radius	0.895+0.041 −0.026[5] R☉
Luminosity	0.62[4] L☉
Temperature	5,477±50[6] K
Metallicity [Fe/H]	+0.26±0.08[6] dex
Rotation	20.34 days[7]
Rotational velocity (v sin i)	45[8] km/s
Age	1.85[9] Gyr
Other designations
EPIC 212157262, K2-187, WISE J085005.65+231133.0, 2MASS J08500566+2311333
Database references
SIMBAD	data

Planetary system

Size comparison of the known planets of K2-187 (artistic concept) with Earth

K2-187 has at least four orbiting exoplanets: two Super-Earths, one Hot Neptune, and one Mini-Neptune. All four planets are in near-resonances with each other and are far too hot for life.

The K2-187 planetary system^{[6][5] [10]}

Companion (in order from star)	Mass	Semimajor axis (AU)	Orbital period (days)	Eccentricity	Inclination	Radius
b	—	0.016322	0.773981+0.000052 −0.000050	—	81.930168+5.825258 −11.735217°	1.30+0.13 −0.13 R🜨
c	—	0.0391185	2.871788+0.000256 −0.000257	—	86.067367+2.836604 −6.998926°	1.80+0.14 −0.14 R🜨
d	—	0.0718533	7.149079+0.000360 −0.000372	—	87.483206+1.886985 −3.903548°	3.17+0.18 −0.18 R🜨
e	—	0.11036	13.608341+0.001661 −0.001580	—	88.970197+0.751147 −1.318388°	2.38+0.18 −0.18 R🜨