Key parameters at a glance
- A radius of 3.90 Earth radii
- A mass of 2,161.24 Earth masses
- Surface gravity around 142.09 g
- An orbital period of 87.645 days
- Semi-major axis 0.4000 AU
- Equilibrium temperature 484 K (211 °C)
- Distance from Earth 5,429.32 light-years
- Earth Similarity Index 0.144
- Travel time at Voyager 1 speed 95,746,110 years
2 siblings around Kepler-31
Kepler-31 d 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-31 b | Neptune-like | 5.50 | 36.74 | 20.861 | 781 | 2011 |
| Kepler-31 c | Neptune-like | 5.30 | 1,493.70 | 42.632 | 615 | 2011 |
| Kepler-31 d this | Sub-Neptune | 3.90 | 2,161.24 | 87.645 | 484 | 2014 |
Kepler-31 d Planet Profile
Physical Specs
Classification
Planet Type
Sub-Neptune
Discovery
Size rank in cohort
Rank by radius
#23of 1978
top 1.1%
This planet
3.90R⊕
Sub-Neptune median
2.71R⊕
Nearest-size peers
| Metric | Earth | Kepler-31 d | Jupiter |
|---|---|---|---|
| Radius (R⊕) | 1.00 | 3.90 | 11.21 |
| Mass (M⊕) | 1.00 | 2,161.24 | 317.83 |
| Density (g/cm³) | 5.51 | 0.08 | 1.33 |
| Surface Gravity (g) | 1.00 | 142.09 | 2.53 |
| Insolation (S⊕) | 1.00 | 11.80 | 0.037 |
Alternative Mass Estimates
| Method | Value | Interpretation |
|---|---|---|
| Best measured mass | 2,161.244 M⊕ | Direct mass measurement (not derived). |
Star Catalogue Identifiers
TIC
TIC 270788519
Gaia DR2
Gaia DR2 2128013019361703936
Gaia DR3
Gaia DR3 2128013019361703936
System
Kepler-31
Percentile among Sub-Neptune cohort
Orbit & Habitability
Orbital Dynamics
Year Length
A year here lasts approximately 87.65 Earth days (24.0% of a terrestrial year) on a nearly circular orbit at a mean orbital distance of 0.4000 AU.
Transit Fingerprint
Depth
0.096 %
Duration
8.256 h
Impact parameter b
0.500
Rp / R★
0.029100
Transit midpoint (BJD)
2,454,967.9420
Photometric dip
Transit produces a flux drop of 959 ppm lasting ≈ 8.26 h.
Extended Orbital Architecture
Planet / star radius ratio
0.029100
Semi-major axis / stellar radius
46.300
Impact parameter (b)
0.500
Transit mid-time (BJD)
2,454,967.9420
Angular separation (arcsec)
0.24000
Eq. Temperature
484K
(211 °C)
Insolation (S⊕)
11.80
Earth = 1.00
Earth Similarity (ESI)
0.144
0 = alien, 1 = Earth-identical
Inside the inner HZ boundary (too hot for liquid water) — the surface is too hot to retain surface water.
Discovery Paper
Primary reference
Rowe et al. 2014Instrument
Kepler CCD Array
Publication
2014-03
Observation locale
Space
Discovery cohort
Planets confirmed in 2014 at Kepler (12 shown).
Host System: Kepler-31
Spectral Class
F-type yellow-white
Effective Temperature
6,340 K — hotter than the Sun (5,778 K)
Estimated Age
0.28 Gyr — younger than the Sun (4.6 Gyr)
Stellar Radius
1.220 R☉
Stellar Mass
1.210 M☉
Metallicity [Fe/H]
-0.08
Extended Stellar Properties
Surface gravity (log g)
4.696 dex
Stellar density
0.610 g/cm³
Metallicity ratio
[Fe/H]
Multi-band Host Photometry — 16 bands
Astrometric Data
Parallax
0.572 mas
Total Proper Motion
7.414 mas/yr
PM Right Ascension
-1.02 mas/yr
PM Declination
-7.34 mas/yr
Galactic Cartesian (pc)
x = 0.284 · y = -0.636 · z = 0.718
Equatorial (J2000)
RA 294.02302° · Dec 45.85305°
Galactic ℓ, b
78.627° · 11.957°
Ecliptic λ, β
313.549° · 65.699°
HTM-20 index
-1489710077
Similar Worlds
K2-63 c
Sub-Neptune · F-type yellow-white
Radius 3.90 R⊕ · 1,688.0 ly
Kepler-1819 b
Sub-Neptune · F-type yellow-white
Radius 3.90 R⊕ · 4,446.1 ly
DMPP-9 b
Sub-Neptune · F-type yellow-white
Radius 3.89 R⊕ · 357.3 ly
Kepler-1736 b
Sub-Neptune · F-type yellow-white
Radius 3.88 R⊕ · 4,664.0 ly
Kepler-1442 b
Sub-Neptune · F-type yellow-white
Radius 3.93 R⊕ · 1,985.2 ly
Kepler-874 b
Sub-Neptune · F-type yellow-white
Radius 3.94 R⊕ · 3,529.5 ly