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Observation data
Epoch       Equinox
Constellation Cygnus
Right ascension 19:49:20.0
Declination +41:53:28
Apparent magnitude (V) 12.4
Spectral type F8 V
Mass 1.25 ± 0.04 M
Radius 1.656 R
Temperature 6116 K
Metallicity [Fe/H] -0.01 ± 0.04 dex
Age 3.9 ± 0.3 Gyr
Other designations
KOI-94, KIC 6462863, 2MASS J19491993+4153280
Database references
KIC data

Kepler-89 is a star with four confirmed planets. Kepler-89 is a possible wide binary star.[1]

Planetary system[edit]

The discovery of four planets orbiting the star was announced October 2012 by analyzing data gathered by Kepler space telescope.[2] Follow-up radial velocity measurements confirmed the existence of Kepler-89d, indicating that Kepler-89d is slightly larger and more massive than Saturn.[3] In October 2013, other three planets were confirmed with Kepler-89c and Kepler-89e getting reasonable mass constraints. Transit-timing variations of the outermost planet suggest that additional planets or minor bodies are present in the system.[4]

In 2012, a partial transit of the second outermost planet by the outermost planet was reported. This was the first time a planet-planet transit in front of the star was detected.[5][2] This allowed to determine the mutual inclination of the planets d and e to be 1.15°.[4]

The Kepler-89 planetary system
(in order from star)
Mass Semimajor axis
Orbital period
Eccentricity Inclination Radius
b <10.5 M 0.05 3.7 89.3° 0.13 RJ
c 7.3-11.8 M 0.099 10.4 <0.1 88.36° 0.31 RJ
d 0.33±0.034 MJ 0.165 22.3 <0.1 89.871° 0.83 RJ
e 11.9-15.5 M 0.298 54.3 <0.1 89.76° 0.49 RJ


  1. ^ Takahashi, Yasuhiro H.; Norio Narita; Teruyuki Hirano; Masayuki Kuzuhara; et al. (2013). "A Discovery of a Candidate Companion to a Transiting System KOI-94: A Direct Imaging Study for a Possibility of a False Positive". arXiv:1309.2559Freely accessible [EP astro-ph. EP]. 
  2. ^ a b Teruyuki Hirano; Norio Narita; Bun'ei Sato; Takahashi, Yasuhiro H.; et al. (2012). "Planet-Planet Eclipse and the Rossiter-McLaughlin Effect of a Multiple Transiting System: Joint Analysis of the Subaru Spectroscopy and the Kepler Photometry". arXiv:1209.4362Freely accessible [astro-ph.EP]. 
  3. ^ Weiss, Lauren M.; Marcy, Geoffrey W.; Rowe, Jason F.; Howard, Andrew W.; Isaacson, Howard; Fortney, Jonathan J.; Miller, Neil; Demory, Brice-Olivier; Fischer, Debra A.; Adams, Elisabeth R.; Dupree, Andrea K.; Howell, Steve B.; Kolbl, Rea; Johnson, John Asher; Horch, Elliott P.; Everett, Mark E.; Fabrycky, Daniel C.; Seager, Sara (2013). "The Mass of KOI-94d and a Relation for Planet Radius, Mass, and Incident Flux". The Astrophysical Journal. 768: 14. arXiv:1303.2150Freely accessible. Bibcode:2013ApJ...768...14W. doi:10.1088/0004-637X/768/1/14. 
  4. ^ a b Masuda, Kento; Hirano, Teruyuki; Taruya, Atsushi; Nagasawa, Makiko; Suto, Yasushi (2013). "Characterization of the KOI-94 System with Transit Timing Variation Analysis: Implication for the Planet-Planet Eclipse". The Astrophysical Journal. 778 (2): 185–200. arXiv:1310.5771v2Freely accessible. Bibcode:2013ApJ...778..185M. doi:10.1088/0004-637X/778/2/185. 
  5. ^ "First ever discovery of planet-planet eclipse | UTokyo Research". Retrieved 2014-01-20.