Kepler-68
Star in the constellation Cygnus
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Kepler-68 is a Sun-like main sequence star located 471 light-years (144 parsecs) away in the constellation Cygnus. It is known to have at least four planets orbiting around it.[6] The third planet has a mass similar to Jupiter but orbits within the habitable zone.[4]
| Observation data Epoch J2000 Equinox J2000 | |
|---|---|
| Constellation | Cygnus[1] |
| Right ascension | 19h 24m 07.76597s[2] |
| Declination | +49° 02′ 24.9283″[2] |
| Apparent magnitude (V) | 10.08[3] |
| Characteristics | |
| Evolutionary stage | Main sequence[4] |
| Spectral type | G1V[5] |
| Astrometry | |
| Radial velocity (Rv) | −20.50±0.23[2] km/s |
| Proper motion (μ) | RA: −7.305 mas/yr[2] Dec.: −10.454 mas/yr[2] |
| Parallax (π) | 6.9298±0.0100 mas[2] |
| Distance | 470.7 ± 0.7 ly (144.3 ± 0.2 pc) |
| Details | |
| Mass | 1.057+0.022 −0.020[6] M☉ |
| Radius | 1.2564±0.0084[6] R☉ |
| Luminosity | 1.55[7] L☉ |
| Temperature | 5847±75[6] K |
| Metallicity [Fe/H] | 0.11±0.03[7] dex |
| Rotational velocity (v sin i) | 2.4[8] km/s |
| Age | 6.84+0.90 −1.04[6] Gyr |
| Other designations | |
| BD+48 2893, KOI-246, KIC 11295426, TYC 3551-189-1, GSC 03551-00189, 2MASS J19240775+4902249[9] | |
| Database references | |
| SIMBAD | data |
| Exoplanet Archive | data |
| KIC | data |
High resolution imaging observations of Kepler-68 carried out with the lucky imaging instrument AstraLux on the 2.2m telescope at Calar Alto Observatory detected a wide companion candidate approximately 11 arcseconds away. Comparing these observations to the 2MASS positions showed that the companion's proper motion appeared consistent with it being bound to the Kepler-68 system, but further observations were needed to confirm this conclusion.[10] In 2019 this was found to be an unrelated background star using Gaia DR2 astrometry.[11]
Planetary system
Currently, four planets have been discovered to orbit around Kepler-68. The two innermost planets were discovered by the planetary transit method. Follow-up Doppler measurements helped to determine the mass of Kepler-68b and helped to discover Kepler-68d.[4][12] There is an additional signal present in the radial velocity measurements indicating another body in the system at a period of greater than 10 years. The mass of this object was initially unknown and it could be either another planet or a stellar companion.[13] In 2023, this fourth planet was confirmed, with a minimum mass about that of Saturn.[6]
| Companion (in order from star) |
Mass | Semimajor axis (AU) |
Orbital period (days) |
Eccentricity | Inclination | Radius |
|---|---|---|---|---|---|---|
| b | 8.03±0.67 M🜨 | 0.06135±0.00043 | 5.39875259 | <0.090 | 87.23+0.22 −0.17° |
2.357±0.023 R🜨 |
| c | <1.3 M🜨 | 0.09008±0.00063 | 9.605027 | <0.099 | 87.071+0.087 −0.094° |
0.979±0.019 R🜨 |
| d | ≥0.749±0.017 MJ | 1.469±0.010 | 632.62±1.03 | 0.102±0.016 | — | — |
| e | ≥0.272±0.032 MJ | 4.60+0.32 −0.16 |
3455+348 −169 |
0.33±0.11 | — | — |