Astronomy:Kepler-18
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Coordinates: 
19h 63m 19.06s, +46° 44′ 47.94″
| Observation data Equinox J2000.0]] (ICRS) | |
|---|---|
| Constellation | Cygnus |
| Right ascension | 19h 52m 19.0688s[1] |
| Declination | +44° 44′ 46.808″[1] |
| Apparent magnitude (V) | 14.0 |
| Characteristics | |
| Spectral type | G7 |
| Astrometry | |
| Proper motion (μ) | RA: −1.432±0.031[1] mas/yr Dec.: −20.313±0.028[1] mas/yr |
| Parallax (π) | 2.2804 ± 0.0168[1] mas |
| Distance | 1,430 ± 10 ly (439 ± 3 pc) |
| Details[2] | |
| 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 | |
| Database references | |
| SIMBAD | data |
| Extrasolar Planets Encyclopaedia | data |
Kepler-18 is a star with almost the same mass as the Sun in the Cygnus constellation.
Planetary system
The star is orbited by 3 confirmed planets, announced in 2011.[2] In 2021, it was found the orbital plane of Kepler-18d is slowly changing, likely under the gravitational influence of the additional giant planet.[4]
| 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⊕ |
References
- ↑ 1.0 1.1 1.2 1.3 1.4 Brown, A. G. A. (August 2018). "Gaia Data Release 2: Summary of the contents and survey properties". Astronomy & Astrophysics 616: A1. doi:10.1051/0004-6361/201833051. Bibcode: 2018A&A...616A...1G. Gaia Data Release 2 catalog entry
- ↑ 2.0 2.1 2.2 Cochran, William D. et al. (2011). "Kepler 18-b, c, and d: A System Of Three Planets Confirmed by Transit Timing Variations, Lightcurve Validation, Spitzer Photometry and Radial Velocity Measurements". The Astrophysical Journal Supplement Series 197 (1): 7. doi:10.1088/0067-0049/197/1/7. Bibcode: 2011ApJS..197....7C.
- ↑ "Kepler-18". SIMBAD. Centre de données astronomiques de Strasbourg. http://simbad.u-strasbg.fr/simbad/sim-basic?Ident=Kepler-18.
- ↑ Shahaf, Sahar; Mazeh, Tsevi; Zucker, Shay; Fabrycky, Daniel (2021), "Systematic search for long-term transit duration changes in Kepler transiting planets", Monthly Notices of the Royal Astronomical Society 505: 1293–1310, doi:10.1093/mnras/stab1359, Bibcode: 2021MNRAS.505.1293S
- ↑ Montet, Benjamin T.; Johnson, John Asher (2013), "Model-Independent Stellar and Planetary Masses from Multi-Transiting Exoplanetary Systems", The Astrophysical Journal 762 (2): 112, doi:10.1088/0004-637X/762/2/112, Bibcode: 2013ApJ...762..112M
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