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Kepler-18

Kepler-18
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: −1.436(14) mas/yr[1]
Dec.: −20.341(14) mas/yr[1]
Parallax (π)2.2804 ± 0.0168 mas[1]
Distance1,430 ± 10 ly
(439 ± 3 pc)
Details[2]
Mass0.972 ± 0.042 M☉
Radius1.108 ± 0.051 R☉
Luminosity0.93 L☉
Surface gravity (log g)4.32 ± 0.12 cgs
Temperature5383 ± 44 K
Metallicity [Fe/H]0.19 ± 0.06 dex
Rotational velocity (v sin i)<4 km/s
Age10.0 ± 2.3 Gyr
Other designations
KOI-137, KIC 8644288,2MASS J19521906+4444467, Gaia DR2 2079295583282164992[3]
Database references
SIMBADdata

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]

The Kepler-18 planetary system[2][5]
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. ^ a b c d Vallenari, A.; et al. (Gaia collaboration) (2023). "Gaia Data Release 3. Summary of the content and survey properties". Astronomy and Astrophysics. 674: A1. arXiv:2208.00211. Bibcode:2023A&A...674A...1G. doi:10.1051/0004-6361/202243940. S2CID 244398875. Gaia DR3 record for this source at VizieR.
  2. ^ 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.
  3. ^ "Kepler-18". SIMBAD. Centre de données astronomiques de Strasbourg. Retrieved 25 January 2018.
  4. ^ 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 (1): 1293–1310, arXiv:2105.04318, Bibcode:2021MNRAS.505.1293S, doi:10.1093/mnras/stab1359
  5. ^ 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
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