Kepler-18

Last updated
Kepler-18
Observation data
Epoch J2000       Equinox J2000
Constellation Cygnus [1]
Right ascension 19h 52m 19.0688s [2]
Declination +44° 44′ 46.808″ [2]
Apparent magnitude  (V)14.0
Characteristics
Spectral type G7
Astrometry
Proper motion (μ)RA: −1.436(14) mas/yr [2]
Dec.: −20.341(14) mas/yr [2]
Parallax (π)2.2804±0.0168  mas [2]
Distance 1,430 ± 10  ly
(439 ± 3  pc)
Details [3]
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
KOI-137, KIC  8644288,2MASS J19521906+4444467, Gaia DR2 2079295583282164992 [4]
Database references
SIMBAD data

Kepler-18 is a star with almost the same mass as the Sun in the Cygnus constellation.

Contents

Planetary system

The star is orbited by 3 confirmed planets, announced in 2011. [3] In 2021, it was found the orbital plane of Kepler-18d is slowly changing, likely under the gravitational influence of the additional giant planet. [5]

The Kepler-18 planetary system [3] [6]
Companion
(in order from star)		 Mass Semimajor axis
(AU)		 Orbital period
(days)		 Eccentricity Inclination Radius
b6.9 ± 3.4  M🜨 0.0447 ± 0.00063.504725 ± 0.000028—84.92 ± 0.26° 2.00 ± 0.10  R🜨
c17.3 ± 1.9  M🜨 0.0752 ± 0.00117.6415716—87.68 ± 0.22° 5.49 ± 0.26  R🜨
d16.4 ± 1.4  M🜨 0.1172 ± 0.001714.858941—88.07 ± 0.1° 6.98 ± 0.33  R🜨

References

  1. ↑ Roman, Nancy G. (1987). "Identification of a constellation from a position". Publications of the Astronomical Society of the Pacific . 99 (617): 695. Bibcode:1987PASP...99..695R. doi: 10.1086/132034 . Constellation record for this object at VizieR.
  2. 1 2 3 4 5 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.
  3. 1 2 3 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.
  4. ↑ "Kepler-18". SIMBAD . Centre de données astronomiques de Strasbourg . Retrieved 25 January 2018.
  5. ↑ 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
  6. ↑ 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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