Kepler-289
Star in Cygnus hosting four planets
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Kepler-289 (PH3) is a rotating variable star slightly more massive than the Sun, with a spectral type of G2, 2370 light-years away from Earth in the constellation of Cygnus. It hosts a system of multiple exoplanets.[3]
| Observation data Epoch J2000.0 Equinox J2000.0 | |
|---|---|
| Constellation | Cygnus[1] |
| Right ascension | 19h 49m 51.6736s[2] |
| Declination | +42° 52′ 58.269″[2] |
| Apparent magnitude (V) | 14.14[3] |
| Characteristics | |
| Evolutionary stage | main sequence[2] |
| Spectral type | G2[4] |
| Variable type | planetary transit |
| Astrometry | |
| Radial velocity (Rv) | −18.21±5.60[2] km/s |
| Proper motion (μ) | RA: 4.815(14) mas/yr[2] Dec.: −0.190(17) mas/yr[2] |
| Parallax (π) | 1.3763±0.0129 mas[2] |
| Distance | 2,370 ± 20 ly (727 ± 7 pc) |
| Details[5] | |
| Mass | 1.08±0.02 M☉ |
| Radius | 1.00±0.02 R☉ |
| Luminosity | 1.15±0.06 L☉ |
| Surface gravity (log g) | 4.47±0.01 cgs |
| Temperature | 5990±38 K |
| Metallicity [Fe/H] | 0.05±0.04 dex |
| Age | 0.65±0.44 Gyr |
| Other designations | |
| PH3, KOI-1353, KIC 7303287, TIC 273234825, 2MASS J19495168+4252582, WISE J194951.68+425258.2[3] | |
| Database references | |
| SIMBAD | data |
| Exoplanet Archive | data |
Planetary system
Kepler-289 hosts three transiting planets, discovered using the Kepler space telescope. Two planets, Kepler-289b and Kepler-289c, were confirmed in 2014 as part of a study using statistical validation to confirm hundreds of Kepler candidates.[6] A third planet, Kepler-289d, was found by the Planet Hunters citizen science project, hence the other designation for the system, PH3.[5]
Different sources present conflicting models of Kepler-289's planetary system. The discovery paper for planet d says that it has an orbital period of 66 days, and that a 330-day candidate is an alias of the true period of planet d.[5] A 2023 follow-up study also reports a 66-day period for planet d.[7] However, a 2025 study reports a 330-day planet, and says that the 66-day signal "is no longer believed to exist in the data".[8] The NASA Exoplanet Archive lists both a 66-day and a 330-day planet, the latter called Kepler-289e,[3] but no literature source claims the existence of more than three planets in the system.
| Companion (in order from star) |
Mass | Semimajor axis (AU) |
Orbital period (days) |
Eccentricity | Inclination | Radius |
|---|---|---|---|---|---|---|
| b | 3.70+3.79 −1.96 M🜨 |
0.21±0.01[5] | 34.5383±0.0006 | — | 88.98+0.06 −0.07° |
2.49±0.07 R🜨 |
| d | 5.33+0.43 −0.42 M🜨 |
0.33±0.02[5] | 66.0282+0.0044 −0.0039 |
— | 89.31±0.04° | 3.03±0.08 R🜨 |
| c | 0.49±0.02 MJ | 0.51±0.03[5] | 125.8723+0.0035 −0.0021 |
— | 89.78±0.04° | 1.002±0.019 RJ |