| Observation data Epoch J2000 Equinox J2000 | |
|---|---|
| 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 mas [1] |
| 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 |
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
- ^ a b c d e Brown, A. G. A.; et al. (Gaia collaboration) (August 2018). "Gaia Data Release 2: Summary of the contents and survey properties". Astronomy & Astrophysics. 616. A1. arXiv: 1804.09365. Bibcode: 2018A&A...616A...1G. doi: 10.1051/0004-6361/201833051. Gaia Data Release 2 catalog entry
- ^ a b c 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. arXiv: 1110.0820. Bibcode: 2011ApJS..197....7C. doi: 10.1088/0067-0049/197/1/7. S2CID 16505452.
- ^ "Kepler-18". SIMBAD. Centre de données astronomiques de Strasbourg. Retrieved 25 January 2018.
- ^ 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, arXiv: 2105.04318, Bibcode: 2021MNRAS.505.1293S, doi: 10.1093/mnras/stab1359
- ^ Montet, Benjamin T.; Johnson, John Asher (2013), "Model-Independent Stellar and Planetary Masses from Multi-Transiting Exoplanetary Systems", The Astrophysical Journal, 762 (2): 112, arXiv: 1211.4028v1, Bibcode: 2013ApJ...762..112M, doi: 10.1088/0004-637X/762/2/112, S2CID 29261765