Astronomy:Kepler-68
| Observation data Equinox J2000.0]] (ICRS) | |
|---|---|
| Constellation | Cygnus |
| Right ascension | 19h 24m 07.76597s[1] |
| Declination | +49° 02′ 24.9283″[1] |
| Apparent magnitude (V) | 10.08[2] |
| Characteristics | |
| Evolutionary stage | Main sequence |
| Spectral type | G1V |
| Astrometry | |
| Radial velocity (Rv) | −20.50±0.23[1] km/s |
| Proper motion (μ) | RA: −7.305[1] mas/yr Dec.: −10.454[1] mas/yr |
| Parallax (π) | 6.9298 ± 0.0100[1] mas |
| Distance | 470.7 ± 0.7 ly (144.3 ± 0.2 pc) |
| Details[3] | |
| Mass | 1.057+0.022 −0.020 M☉ |
| Radius | 1.2564±0.0084 R☉ |
| Temperature | 5847±75 K |
| Metallicity [Fe/H] | 0.11±0.06 dex |
| Rotational velocity (v sin i) | 2.4±0.5[4] km/s |
| Age | 6.84+0.90 −1.04 Gyr |
| Other designations | |
| Database references | |
| SIMBAD | data |
| KIC | data |
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.[3] The third planet has a mass similar to Jupiter but orbits within the habitable zone.[5]
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 shows that the companions proper motion is consistent with it being bound to the Kepler-68 system, but further observations are needed to confirm this conclusion.[6] Eleven arcseconds at the distance of Kepler-68 leads to a sky projected separation of approximately 1600 Astronomical units. A circular orbit at that distance would have a period of roughly 50,000 years.[7]
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.[5][8] 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.[7] In 2023, this fourth planet was confirmed, with a minimum mass about that of Saturn.[3]
| 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 | — | — |
References
- ↑ 1.0 1.1 1.2 1.3 1.4 Vallenari, A. et al. (2022). "Gaia Data Release 3. Summary of the content and survey properties". Astronomy & Astrophysics. doi:10.1051/0004-6361/202243940 Gaia DR3 record for this source at VizieR.
- ↑ Høg, E. (2000). "The Tycho-2 catalogue of the 2.5 million brightest stars". Astronomy and Astrophysics 355: L27–L30. Bibcode: 2000A&A...355L..27H.
- ↑ 3.0 3.1 3.2 3.3 Bonomo, A. S. et al. (April 2023). "Cold Jupiters and improved masses in 38 Kepler and K2 small-planet systems from 3661 high-precision HARPS-N radial velocities. No excess of cold Jupiters in small-planet systems". Astronomy & Astrophysics. doi:10.1051/0004-6361/202346211.
- ↑ 4.0 4.1 "Kepler-68". SIMBAD. Centre de données astronomiques de Strasbourg. http://simbad.u-strasbg.fr/simbad/sim-basic?Ident=Kepler-68.
- ↑ 5.0 5.1 Gilliland, Ronald L. et al. (2013). "Kepler-68: Three Planets, One with a Density Between That of Earth and Ice Giants". The Astrophysical Journal 766 (1): 40. doi:10.1088/0004-637X/766/1/40. Bibcode: 2013ApJ...766...40G.
- ↑ Ginski, C. et al. (2016). "A lucky imaging multiplicity study of exoplanet host stars – II". Monthly Notices of the Royal Astronomical Society 457 (2): 2173–2191. doi:10.1093/mnras/stw049. Bibcode: 2016MNRAS.457.2173G. https://academic.oup.com/mnras/article/457/2/2173/968721.
- ↑ 7.0 7.1 Mills, Sean M. et al. (2019). "Long-period Giant Companions to Three Compact, Multiplanet Systems". The Astronomical Journal 157 (4): 145. doi:10.3847/1538-3881/ab0899. Bibcode: 2019AJ....157..145M.
- ↑ Marcy, Geoffrey W. et al. (2014). "Masses, Radii, and Orbits of Small Kepler Planets: The Transition from Gaseous to Rocky Planets". The Astrophysical Journal Supplement Series 210 (2): 20. doi:10.1088/0067-0049/210/2/20. Bibcode: 2014ApJS..210...20M.
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