Key parameters at a glance
- A radius of 9.80 Earth radii
- A mass of 181.00 Earth masses
- Surface gravity around 1.88 g
- An orbital period of 21.402 days
- Semi-major axis 0.1652 AU
- Equilibrium temperature 1,087 K (814 °C)
- Distance from Earth 2,977.78 light-years
- Earth Similarity Index 0.146
- Travel time at Voyager 1 speed 52,513,230 years
- Almost certainly tidally locked to its host star given the close orbit
2 siblings around Kepler-56
Kepler-56 c shares its host star with 2 other confirmed planets. Side-by-side measurements below.
| Planet | Type | Radius (R⊕) | Mass (M⊕) | Period (d) | Eq. T (K) | Year |
|---|---|---|---|---|---|---|
| Kepler-56 b | Neptune-like | 6.51 | 22.10 | 10.502 | 1,378 | 2012 |
| Kepler-56 c this | Neptune-like | 9.80 | 181.00 | 21.402 | 1,087 | 2012 |
| Kepler-56 d | Gas Giant | 12.80 | 1,784.00 | 1,002.000 | — | 2016 |
Kepler-56 c Planet Profile
Physical Specs
Classification
Planet Type
Neptune-like
Discovery
Size rank in cohort
Rank by radius
#17of 574
top 2.8%
This planet
9.80R⊕
Neptune-like median
6.39R⊕
Nearest-size peers
| Metric | Earth | Kepler-56 c | Jupiter |
|---|---|---|---|
| Radius (R⊕) | 1.00 | 9.80 | 11.21 |
| Mass (M⊕) | 1.00 | 181.00 | 317.83 |
| Density (g/cm³) | 5.51 | 1.06 | 1.33 |
| Surface Gravity (g) | 1.00 | 1.88 | 2.53 |
| Insolation (S⊕) | 1.00 | 317.21 | 0.037 |
Alternative Mass Estimates
| Method | Value | Interpretation |
|---|---|---|
| Best measured mass | 181.000 M⊕ | Direct mass measurement (not derived). |
| Minimum mass (M sin i) | 235.585 M⊕ | Lower bound from radial-velocity fitting. |
Star Catalogue Identifiers
TIC
TIC 138430034
Gaia DR2
Gaia DR2 2077617930392844800
Gaia DR3
Gaia DR3 2077617930392844800
System
Kepler-56
Percentile among Neptune-like cohort
Orbit & Habitability
Orbital Dynamics
Year Length
A year here lasts approximately 21.40 Earth days (5.9% of a terrestrial year) on a nearly circular orbit at a mean orbital distance of 0.1652 AU.
Transit Fingerprint
Depth
0.041 %
Duration
11.721 h
Impact parameter b
0.943
Rp / R★
0.022920
Transit midpoint (BJD)
2,454,978.6560
Photometric dip
Transit produces a flux drop of 409 ppm lasting ≈ 11.72 h.
Extended Orbital Architecture
Planet / star radius ratio
0.022920
Semi-major axis / stellar radius
5.660
Impact parameter (b)
0.943
RV semi-amplitude (K)
38.516 m/s
Transit mid-time (BJD)
2,454,978.6560
Long. of periastron (ω)
-97.40°
Angular separation (arcsec)
0.18100
Eq. Temperature
1,087K
(814 °C)
Insolation (S⊕)
317.21
Earth = 1.00
Earth Similarity (ESI)
0.146
0 = alien, 1 = Earth-identical
Inside the inner HZ boundary (too hot for liquid water) — the dayside is scorched. Close-orbiting tidally-locked around a cool host.
Detection Signatures
Transit photometry
A transit dip has been observed from at least one telescope.
Transit timing variations
Gravitational interactions from neighbours have been detected.
Discovery Paper
Primary reference
Steffen et al. 2013Instrument
Kepler CCD Array
Publication
2013-01
Observation locale
Space
Discovery cohort
Planets confirmed in 2012 at Kepler (12 shown).
Host System: Kepler-56
Spectral Class
K-type orange
Effective Temperature
4,840 K — cooler than the Sun (5,778 K)
Estimated Age
3.50 Gyr — younger than the Sun (4.6 Gyr)
Stellar Radius
4.230 R☉
Stellar Mass
1.320 M☉
Metallicity [Fe/H]
0.20
Extended Stellar Properties
Surface gravity (log g)
3.310 dex
Stellar density
0.025 g/cm³
Systemic radial velocity
-54.30 km/s
Metallicity ratio
[Fe/H]
Multi-band Host Photometry — 16 bands
Astrometric Data
Parallax
1.067 mas
Total Proper Motion
13.788 mas/yr
PM Right Ascension
-6.75 mas/yr
PM Declination
-12.02 mas/yr
Galactic Cartesian (pc)
x = 0.300 · y = -0.682 · z = 0.667
Equatorial (J2000)
RA 293.75830° · Dec 41.87181°
Galactic ℓ, b
74.926° · 10.314°
Ecliptic λ, β
309.818° · 62.066°
HTM-20 index
-872674545
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