Kepler-18
Star in the constellation Cygnus
From Wikipedia, the free encyclopedia
Kepler-18 is a star with almost the same mass as the Sun in the Cygnus constellation.
Right ascension19h 52m 19.0688s[2]
Declination+44° 44′ 46.808″[2]
Apparentmagnitude(V)14.0[citation needed]
| Observation data Epoch J2000 Equinox J2000 | |
|---|---|
| Constellation | Cygnus[1] |
| Right ascension | 19h 52m 19.0688s[2] |
| Declination | +44° 44′ 46.808″[2] |
| Apparent magnitude (V) | 14.0[citation needed] |
| Characteristics | |
| Evolutionary stage | main sequence[2] |
| Spectral type | G7[citation needed] |
| Astrometry | |
| Proper motion (μ) | RA: −1.436(14) mas/yr[2] Dec.: −20.341(14) mas/yr[2] |
| Parallax (π) | 2.2804±0.0168 mas[2] |
| Distance | 1,430 ± 10 ly (439 ± 3 pc) |
| Details[3] | |
| Mass | 0.972 ± 0.042 M☉ |
| Radius | 1.108 ± 0.051 R☉ |
| Luminosity | 0.93 L☉ |
| Surface gravity (log g) | 4.32 ± 0.12 cgs |
| Temperature | 5383 ± 44 K |
| Metallicity [Fe/H] | 0.19 ± 0.06 dex |
| Rotational velocity (v sin i) | <4 km/s |
| Age | 10.0 ± 2.3 Gyr |
| Other designations | |
| KOI-137, KIC 8644288,2MASS J19521906+4444467, Gaia DR2 2079295583282164992[4] | |
| Database references | |
| SIMBAD | data |
| Exoplanet Archive | data |
Planetary system
The star is orbited by 3 confirmed planets, announced in 2011.[3] In 2021, it was found the orbital plane of Kepler-18d is slowly changing, likely under the gravitational influence of the additional giant planet.[5]
| Companion (in order from star) |
Mass | Semimajor axis (AU) |
Orbital period (days) |
Eccentricity | Inclination | Radius |
|---|---|---|---|---|---|---|
| b | 6.9 ± 3.4 M🜨 | 0.0447 ± 0.0006 | 3.504725 ± 0.000028 | — | 84.92 ± 0.26° | 2.00 ± 0.10 R🜨 |
| c | 17.3 ± 1.9 M🜨 | 0.0752 ± 0.0011 | 7.6415716 | — | 87.68 ± 0.22° | 5.49 ± 0.26 R🜨 |
| d | 16.4 ± 1.4 M🜨 | 0.1172 ± 0.0017 | 14.858941 | — | 88.07 ± 0.1° | 6.98 ± 0.33 R🜨 |