Kepler-84

Kepler-84 is a Sun-like star 4,700 light-years from the Sun. It is a G-type star. The stellar radius measurement has a large uncertainty of 48% as in 2017, complicating the modelling of the star.^[5] The Kepler-84 star has two suspected stellar companions. Four red dwarfs are few arcseconds away and at least one is probably gravitationally bound to Kepler-84.^[6] Another (which is a background star with a probability 0.5%) is a yellow star of mass 0.855M_☉ on projected separations of 0.18±0.05″ or 0.26″ (213.6 AU).^[7]

Kepler-84

Observation data Epoch J2000      Equinox J2000
Constellation	Cygnus
Right ascension	01^h 37^m 40.87964^s^[1]
Declination	+12° 04′ 42.1742″^[1]
Characteristics
Spectral type	G3^[2]
Astrometry
Proper motion (μ)	RA: −0.150 mas/yr Dec.: −2.872 mas/yr
Parallax (π)	0.6929 ± 0.7043 mas
Details
Mass	1^[2] M☉
Radius	1.2 R☉
Temperature	5,755^[3] K
Metallicity [Fe/H]	+0.09 ± 0.04^[2] dex
Age	4.9^[4] Gyr
Other designations
Kepler-84, KOI-1589, Gaia DR2 2073776859551124992, KIC 5301750, 2MASS J19530049+4029458^[1]
Database references
SIMBAD	data
ARICNS	data

Planetary system

Kepler-84 is orbited by five known planets, four small gas giants and a Super-Earth. Planets Kepler-84b and Kepler-84c were confirmed in 2012^[8] while the rest was confirmed in 2014.^[9] To keep the known planetary system stable, no additional giant planets can be located within 7.4 AU from the parent stars.^[10]

The Kepler-84 planetary system^{[11][12][13][14]}

Companion (in order from star)	Mass	Semimajor axis (AU)	Orbital period (days)	Eccentricity	Inclination	Radius
b	0.126±0.038 MJ	0.083	8.725854±0.00006	0	88.24°	0.174±0.045 RJ
c	0.064±0.037 MJ	0.108	12.882525±0.000093	0	88.24°	0.184±0.047 RJ
d	—	0.052	4.224537±0.000042	—	—	0.123±0.024 RJ
e	—	0.181	27.434389±0.000224	—	—	0.232±0.044 RJ
f	—	0.25	44.552169±0.000812	—	—	0.196±0.038 RJ

References

1. "Kepler-84". SIMBAD. Centre de données astronomiques de Strasbourg. Retrieved July 13, 2016.
2. Vidotto, A. A; Gregory, S. G; Jardine, M; Donati, J. F; Petit, P; Morin, J; Folsom, C. P; Bouvier, J; Cameron, A. C; Hussain, G; Marsden, S; Waite, I. A; Fares, R; Jeffers, S; Do Nascimento, J. D (2014). "Stellar magnetism: Empirical trends with age and rotation" (PDF). Monthly Notices of the Royal Astronomical Society. 441 (3): 2361. arXiv:1404.2733. Bibcode:2014MNRAS.441.2361V. doi:10.1093/mnras/stu728. S2CID 43200119.
3. Gray, R. O; Corbally, C. J; Garrison, R. F; McFadden, M. T; Robinson, P. E (2003). "Contributions to the Nearby Stars (NStars) Project: Spectroscopy of Stars Earlier than M0 within 40 parsecs: The Northern Sample I". The Astronomical Journal. 126 (4): 2048. arXiv:astro-ph/0308182. Bibcode:2003AJ....126.2048G. doi:10.1086/378365. S2CID 119417105.
4. Melendez, Jorge; Dodds-Eden, Katie; Robles, Jose A (2006). "HD 98618: A Star Closely Resembling our Sun". The Astrophysical Journal. 641 (2): L133–L136. arXiv:astro-ph/0603219. Bibcode:2006ApJ...641L.133M. doi:10.1086/503898. S2CID 17479387.
5. Ramos, X. S.; Charalambous, C.; Benítez-Llambay, P.; Beaugé, C. (2017), "Planetary migration and the origin of the 2:1 and 3:2 (near)-resonant population of close-in exoplanets", Astronomy & Astrophysics, 602: A101, arXiv:1704.06459, Bibcode:2017A&A...602A.101R, doi:10.1051/0004-6361/201629642, S2CID 119369796
6. Hirsch, Lea A.; Ciardi, David R.; Howard, Andrew W.; Everett, Mark E.; Furlan, Elise; Saylors, Mindy; Horch, Elliott P.; Howell, Steve B.; Teske, Johanna; Marcy, Geoffrey W. (2017), "ASSESSING THE EFFECT OF STELLAR COMPANIONS FROM HIGH-RESOLUTION IMAGING OF Kepler OBJECTS OF INTEREST", The Astronomical Journal, 153 (3): 117, arXiv:1701.06577, Bibcode:2017AJ....153..117H, doi:10.3847/1538-3881/153/3/117, S2CID 39321033
7. Kraus, Adam L.; Ireland, Michael J.; Huber, Daniel; Mann, Andrew W.; Dupuy, Trent J. (2016), "The Impact of Stellar Multiplicity on Planetary Systems. I. The Ruinous Influence of Close Binary Companions", The Astronomical Journal, 152 (1): 8, arXiv:1604.05744, Bibcode:2016AJ....152....8K, doi:10.3847/0004-6256/152/1/8, S2CID 119110229
8. Xie, Ji-Wei (2012), "Transit Timing Variation of Near-Resonance Planetary Pairs: Confirmation of 12 Multiple-Planet Systems", The Astrophysical Journal Supplement Series, 208 (2): 22, arXiv:1208.3312, Bibcode:2013ApJS..208...22X, doi:10.1088/0067-0049/208/2/22, S2CID 17160267
9. openexoplanetcatalogue.com Kepler-84
10. Becker, Juliette C.; Adams, Fred C. (2017), "Effects of Unseen Additional Planetary Perturbers on Compact Extrasolar Planetary Systems", Monthly Notices of the Royal Astronomical Society, 468 (1): 549–563, arXiv:1702.07714, Bibcode:2017MNRAS.468..549B, doi:10.1093/mnras/stx461, S2CID 119325005
11. Furlan, E.; Howell, S. B. (2017), "The densities of planets in multiple stellar systems", The Astronomical Journal, 154 (2): 66, arXiv:1707.01942, Bibcode:2017AJ....154...66F, doi:10.3847/1538-3881/aa7b70, S2CID 28833730
12. Planet Kepler-84 d at exoplanets.eu
13. Planet Kepler-84 e at exoplanets.eu
14. Planet Kepler-84 f at exoplanets.eu