Kepler-27

Kepler-27 is a star in the northern constellation of Cygnus, the swan. It is located at the celestial coordinates: Right Ascension 19^h 28^m 56.81962^s, Declination +41° 05′ 09.1405″.^[2] With an apparent visual magnitude of 15.855,^[3] this star is too faint to be seen with the naked eye. In 2024, Kepler-27 was discovered to be a binary star with a red dwarf companion 1.975 arcseconds away.^[8]

Kepler-27

Observation data Epoch J2000      Equinox J2000
Constellation	Cygnus[1]
Right ascension	19h 28m 56.81962s[2]
Declination	+41° 05′ 09.1405″[2]
Apparent magnitude (V)	15.855[3]
Characteristics
Spectral type	G5[4]
Astrometry
Proper motion (μ)	RA: 2.171±0.033 mas/yr[2] Dec.: −0.324±0.031 mas/yr[2]
Parallax (π)	0.9298±0.0281 mas[2]
Distance	3,500 ± 100 ly (1,080 ± 30 pc)
Details
Mass	0.9+0.03 −0.10[5] M☉
Radius	0.850+0.017 −0.016[6] R☉
Temperature	5,249+68 −56[6] K
Metallicity [Fe/H]	0.250+0.064 −0.061[6] dex
Rotational velocity (v sin i)	0.6±5.0[7] km/s
Age	1.620+0.978 −0.466[6] Gyr
Other designations
KOI-841, KIC 5792202, 2MASS J19285682+4105091, Gaia DR2 2053586321364864640
Database references
SIMBAD	data
KIC	data

Planetary system

The planetary system of Kepler-27 comprising two small gas giants on eccentric orbits^[5] was discovered in late 2011.^[7] The planets Kepler-27b and Kepler-27c have equilibrium temperatures of 610 K and 481 K, respectively.^[9] In 2021, a third, sub-Neptune-sized planet was confirmed, orbiting closer in than the other two planets.^[10][11]

The Kepler-27 planetary system^[9][11]

Companion (in order from star)	Mass	Semimajor axis (AU)	Orbital period (days)	Eccentricity	Inclination	Radius
d	—	—	6.54629	—	—	0.2414 RJ
b	0.1320±0.018 MJ	0.118	15.3348	—	—	0.522±0.024 RJ
c	0.0670±0.011 MJ	0.191	31.3309	—	—	0.640±0.029 RJ