Kepler-68

Summary

Kepler-68
Observation data
Epoch J2000      Equinox J2000
Constellation Cygnus
Right ascension 19h 24m 07.7660s[1]
Declination +49° 02′ 24.9282″[1]
Apparent magnitude (V) 10.08[2]
Characteristics
Evolutionary stage Main sequence
Spectral type G1V C
Astrometry
Proper motion (μ) RA: −7.334 ± 0.039[1] mas/yr
Dec.: −10.430 ± 0.048[1] mas/yr
Parallax (π)6.9076 ± 0.0208[1] mas
Distance472 ± 1 ly
(144.8 ± 0.4 pc)
Details[3]
Mass1.079±0.051 M
Radius1.243±0.019 R
Temperature5793±74 K
Metallicity [Fe/H]0.12 (± 0.074) dex
Rotational velocity (v sin i)2.4±0.5[4] km/s
Age6.31+0.84
−0.79
 Gyr
Other designations
BD+48 2893, KOI-246, KIC 11295426, TYC 3551-189-1, GSC 03551-00189, 2MASS J19240775+4902249[4]
Database references
SIMBADdata
KICdata

Kepler-68 is a Sun-like main sequence star. It is known to have at least three planets orbiting around it. The outermost planet has a mass similar to Jupiter but orbits within the habitable zone.[5]

High resolution imaging observations of Kepler-68 carried out with the lucky imaging instrument AstraLux on the 2.2m telescope at Calar Alto Observatory detected a wide companion candidate approximately 11 arcseconds away. Comparing these observations to the 2MASS positions shows that the companions proper motion is consistent with it being bound to the Kepler-68 system, but further observations are needed to confirm this conclusion.[6] Eleven arcseconds at the distance of Kepler-68 leads to a sky projected separation of approximately 1600 Astronomical units. A circular orbit at that distance would have a period of roughly 50,000 years.[7]

Planetary system

The Kepler-68 planetary system[7][5]
Companion
(in order from star)
Mass Semimajor axis
(AU)
Orbital period
(days)
Eccentricity Inclination Radius
b 7.65+1.37
−1.32
 M
0.06170±0.00056 5.398763 87.60±0.90° 2.31+0.06
−0.09
 R
c 2.02+1.72
−1.78
 M
0.09059±0.00082 9.605065 86.93±0.41° 0.953+0.037
−0.042
 R
d ≥0.77±0.03 MJ 1.40±0.03 634.6+4.1
−3.7
0.112+0.035
−0.034
e (unconfirmed) ~5? >3650

Currently, three planets have been discovered to orbit around Kepler-68. Two of the innermost planets were discovered by the planetary transit method. Follow-up Doppler measurements helped to determine the mass of Kepler-68b and helped to discover Kepler-68d.[8] There is an additional signal present in the radial velocity measurements indicating another body in the system at a period of greater than 10 years. The mass of this object is unknown and it could be either another planet or a stellar companion.[7]

References

  1. ^ 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 DR2 record for this source at VizieR.
  2. ^ Høg, E. (2000). "The Tycho-2 catalogue of the 2.5 million brightest stars". Astronomy and Astrophysics. 355: L27–L30. Bibcode:2000A&A...355L..27H.
  3. ^ "Notes on Kepler-68 b". Retrieved 17 January 2016.
  4. ^ a b "Kepler-68". SIMBAD. Centre de données astronomiques de Strasbourg. Retrieved 2019-10-16.
  5. ^ a b Gilliland, Ronald L.; et al. (2013). "Kepler-68: Three Planets, One with a Density Between That of Earth and Ice Giants". The Astrophysical Journal. 766 (1). 40. arXiv:1302.2596. Bibcode:2013ApJ...766...40G. doi:10.1088/0004-637X/766/1/40.
  6. ^ Ginski, C.; et al. (2016). "A lucky imaging multiplicity study of exoplanet host stars – II". Monthly Notices of the Royal Astronomical Society. 457 (2): 2173–2191. arXiv:1601.01524. Bibcode:2016MNRAS.457.2173G. doi:10.1093/mnras/stw049.
  7. ^ a b c Mills, Sean M.; et al. (2019). "Long-period Giant Companions to Three Compact, Multiplanet Systems". The Astronomical Journal. 157 (4). 145. arXiv:1903.07186. Bibcode:2019AJ....157..145M. doi:10.3847/1538-3881/ab0899. S2CID 119197547.
  8. ^ Marcy, Geoffrey W.; et al. (2014). "Masses, Radii, and Orbits of Small Kepler Planets: The Transition from Gaseous to Rocky Planets". The Astrophysical Journal Supplement Series. 210 (2). 20. arXiv:1401.4195. Bibcode:2014ApJS..210...20M. doi:10.1088/0067-0049/210/2/20.