Kepler-68

Short description: Star in the constellation Cygnus

Kepler-68  Observation data
Equinox J2000.0]] (ICRS)

Constellation | Cygnus
Right ascension |  19h 24m 07.76597s[1]
Declination | +49° 02′ 24.9283″[1]
Apparent magnitude (V) | 10.08[2]
Characteristics
Evolutionary stage | Main sequence
Spectral type | G1V
Astrometry
Radial velocity (Rv)| −20.50±0.23[1] km/s
Proper motion (μ)|  RA: −7.305[1] mas/yr
Dec.: −10.454[1] mas/yr
Parallax (π)| 6.9298 ± 0.0100[1] mas
Distance| 470.7 ± 0.7 ly
(144.3 ± 0.2 pc)
Details[3]
Mass| 1.057+0.022
−0.020 M☉
Radius| 1.2564±0.0084 R☉
Temperature| 5847±75 K
Metallicity [Fe/H]| 0.11±0.06 dex
Rotational velocity (v sin i)| 2.4±0.5[4] km/s
Age| 6.84+0.90
−1.04 Gyr
Other designations

BD+48 2893, KOI-246, KIC 11295426, TYC 3551-189-1, GSC 03551-00189, 2MASS J19240775+4902249[4]

Database references
SIMBAD| data
KIC| data

Kepler-68 is a Sun-like main sequence star located 471 light-years (144 parsecs) away in the constellation Cygnus. It is known to have at least four planets orbiting around it.[3] The third 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

Currently, four planets have been discovered to orbit around Kepler-68. The two 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.[5][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 was initially unknown and it could be either another planet or a stellar companion.[7] In 2023, this fourth planet was confirmed, with a minimum mass about that of Saturn.[3]

The Kepler-68 planetary system[3] Companion
(in order from star) | Mass | Semimajor axis
(AU) | Orbital period
(days) | Eccentricity | Inclination | Radius

|
|
|
|
|
|

b | 8.03±0.67 M⊕ | 0.06135±0.00043 | 5.39875259 | <0.090  | 87.23+0.22
−0.17° | 2.357±0.023 R⊕
c | <1.3 M⊕ | 0.09008±0.00063 | 9.605027 | <0.099  | 87.071+0.087
−0.094° | 0.979±0.019 R⊕
d | ≥0.749±0.017 MJ | 1.469±0.010 | 632.62±1.03 | 0.102±0.016 | —  | —
e | ≥0.272±0.032 MJ | 4.60+0.32
−0.16 | 3455+348
−169 | 0.33±0.11 | —  | —

## References

1. ↑ 1.0 1.1 1.2 1.3 1.4 Vallenari, A. et al. (2022). "Gaia Data Release 3. Summary of the content and survey properties". Astronomy & Astrophysics. doi:10.1051/0004-6361/202243940 Gaia DR3 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. ↑ 3.0 3.1 3.2 3.3 Bonomo, A. S. et al. (April 2023). "Cold Jupiters and improved masses in 38 Kepler and K2 small-planet systems from 3661 high-precision HARPS-N radial velocities. No excess of cold Jupiters in small-planet systems". Astronomy & Astrophysics. doi:10.1051/0004-6361/202346211.
4. ↑ 4.0 4.1 "Kepler-68". SIMBAD. Centre de données astronomiques de Strasbourg. http://simbad.u-strasbg.fr/simbad/sim-basic?Ident=Kepler-68.
5. ↑ 5.0 5.1 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. doi:10.1088/0004-637X/766/1/40. Bibcode: 2013ApJ...766...40G.
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. doi:10.1093/mnras/stw049. Bibcode: 2016MNRAS.457.2173G. https://academic.oup.com/mnras/article/457/2/2173/968721.
7. ↑ 7.0 7.1 Mills, Sean M. et al. (2019). "Long-period Giant Companions to Three Compact, Multiplanet Systems". The Astronomical Journal 157 (4): 145. doi:10.3847/1538-3881/ab0899. Bibcode: 2019AJ....157..145M.
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. doi:10.1088/0067-0049/210/2/20. Bibcode: 2014ApJS..210...20M.

* v
* t
* e

Kepler-68 system

Stars|

* Kepler-68

Planets|

* Kepler-68b
* Kepler-68c
* Kepler-68d

* v
* t
* e

Constellation of Cygnus

* List of stars in Cygnus

Stars|

| Bayer|

* α (Deneb)
* β (Albireo)
* γ (Sadr)
* δ (Fawaris)
* ε (Aljanah)
* ζ
* η
* θ
* ι1
* ι2
* κ
* λ
* μ
* ν
* ξ
* π1 (Azelfafage)
* π2
* ρ
* σ
* τ
* υ
* φ
* χ
* ψ
* ω1
* ω2
* P
* Q

|

Flamsteed|

* 2
* 4
* 8
* 9
* 14
* 15
* 16 (c)
* 17
* 20 (d)
* 22
* 23
* 26 (e)
* 27 (b1)
* 28 (b2)
* 29 (b3)
* 30
* 31
* 32
* 33
* 35
* 39
* 41
* 47
* 52
* 55
* 56
* 57
* 59 (f1)
* 61
* 63 (f2)
* 68 (A)
* 71 (g)
* 72
* 74
* 75

Variable|

* R
* T
* W
* RW
* SS
* TT
* BC
* BI
* CH
* KY
* V404
* V476
* V1057
* V1143
* V1191
* V1489
* V1500
* V1668
* V1974
* V2513

HR|

* 7633
* 7912
* 8193

HD|

* 185269
* 185435
* 187123
* 188753
* 191806

Gliese|

* 777
* 806
* 1245

Kepler|

* 5
* 6
* 11
* 15
* 16
* 17
* 18
* 22
* 23
* 27
* 28
* 29
* 31
* 32
* 33
* 34
* 35
* 36
* 39
* 40
* 41
* 42
* 43
* 44
* 45
* 47
* 51
* 56
* 61
* 66
* 67
* 68
* 69
* 70
* 78
* 80
* 84
* 86
* 89
* 107
* 182
* 186
* 223
* 371
* 419
* 432
* 451
* 452
* 1229
* 1520
* 1625

Other|

* AFGL 2591
* BD+40° 4210
* BD+43 3654
* Cygnus OB2 #8A
* Cygnus OB2 #12
* Cygnus X-1
* Cygnus X-3
* G 208-44
* G 208-45
* HAT-P-7
* HAT-P-11
* HAT-P-17
* KELT-9
* KIC 8462852
* KIC 9832227
* KIC 11026764
* KOI-74
* KOI-81
* KOI-256
* KPD 1930+2752
* MWC 349
* N6946-BH1
* NML Cygni
* PH1
* PSR J2032+4127
* W75N(B)-VLA2
* WISE J2000+3629
* WR 134
* WR 135
* WR 136
* WR 137
* WR 140
* WR 142
* WR 147
* WR 148

Former|

* 3

Star
clusters|

| Association|

* Cygnus OB2
* Cygnus OB7

|

Open|

* DR 6
* IC 5146
* Messier 29
* Messier 39
* NGC 6811
* NGC 6819
* NGC 6834
* NGC 6866
* NGC 6871
* NGC 6910

Molecular
clouds|

* Cygnus X (including DR 21)

Nebulae|

| Dark|

* Barnard 146
* Barnard 147
* IC 5146
* L1014

|

H II|

* NGC 6914
* North America Nebula
* Pelican Nebula
* Sadr Region
* Sh2-101
* Sh2-106

Planetary|

* Abell 78
* Egg Nebula
* IRAS 19475+3119
* Kronberger 61
* M1-92
* NGC 6826
* NGC 6881
* NGC 6884
* NGC 7008
* NGC 7026
* NGC 7027
* NGC 7048
* Soap Bubble Nebula

WR|

* Crescent Nebula

SNR|

* Cygnus Loop (including Veil Nebula)

Galaxies|

| NGC|

* 6801
* 6946
* 7013

|

Other|

* 3C 438
* Cygnus A

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