Kepler-84

Kepler-84 is a Sun-like star 3,339 light-years from the Sun.^[6] It is a G-type star. The stellar radius measurement has a large uncertainty of 48% as in 2017, complicating the modelling of the star.^[7] The Kepler-84 star has two suspected stellar companions. Four stars, all more than four magnitudes fainter than Kepler-84, are seen within a few arcseconds and at least one is probably gravitationally bound to Kepler-84.^[8] Another, which has only a 0.005% chance of being a background star, is a yellow star with mass 0.855 M_☉ at a projected separation of 0.18±0.05″ or 0.26″ (213.6 AU).^[9]

Kepler-84

Observation data Epoch J2000      Equinox J2000
Constellation	Cygnus[1]
Right ascension	19h 53m 00.48519s[2]
Declination	+40° 29′ 45.9477″[2]
Apparent magnitude (V)	15.03[3]
Characteristics
Astrometry
Proper motion (μ)	RA: −0.150 mas/yr[2] Dec.: −2.872 mas/yr[2]
Parallax (π)	0.6929±0.7043 mas[2]
Distance	1,066[4] pc
Details
Other designations
Kepler-84, KOI-1589, KIC 5301750, 2MASS J19530049+4029458[5]
Database references
SIMBAD	data
Exoplanet Archive	data

Planetary system

Kepler-84 is orbited by five known planets, four small gas giants and a Super-Earth. Planets Kepler-84b and Kepler-84c were confirmed in 2012^[10] while the rest was confirmed in 2014.^[11] To keep the known planetary system stable, no additional giant planets can be located within 7.4 AU from the parent stars.^[12]

The Kepler-84 planetary system^{[13][14][15][16]}

Companion (in order from star)	Mass	Semimajor axis (AU)	Orbital period (days)	Eccentricity	Inclination	Radius
b	0.126±0.038 MJ	0.083	8.725854±0.00006	0	88.24°	0.174±0.045 RJ
c	0.064±0.037 MJ	0.108	12.882525±0.000093	0	88.24°	0.184±0.047 RJ
d	—	0.052	4.224537±0.000042	—	—	0.123±0.024 RJ
e	—	0.181	27.434389±0.000224	—	—	0.232±0.044 RJ
f	—	0.25	44.552169±0.000812	—	—	0.196±0.038 RJ