Key parameters at a glance
- A radius of 11.88 Earth radii
- A mass of 563.83 Earth masses
- Surface gravity around 3.99 g
- An orbital period of 1.258 days
- Semi-major axis 0.0220 AU
- Equilibrium temperature 1,688 K (1415 °C)
- Distance from Earth 360.49 light-years
- Earth Similarity Index 0.033
- Travel time at Voyager 1 speed 6,357,249 years
K2-31 b Planet Profile
Physical Specs
Classification
Planet Type
Gas Giant
Discovery
Size rank in cohort
Rank by radius
#1547of 1771
top 87.3%
This planet
11.88R⊕
Gas Giant median
13.52R⊕
Nearest-size peers
| Metric | Earth | K2-31 b | Jupiter |
|---|---|---|---|
| Radius (R⊕) | 1.00 | 11.88 | 11.21 |
| Mass (M⊕) | 1.00 | 563.83 | 317.83 |
| Density (g/cm³) | 5.51 | 0.03 | 1.33 |
| Surface Gravity (g) | 1.00 | 3.99 | 2.53 |
| Insolation (S⊕) | 1.00 | 1,272.00 | 0.037 |
Alternative Mass Estimates
| Method | Value | Interpretation |
|---|---|---|
| Best measured mass | 563.830 M⊕ | Direct mass measurement (not derived). |
Star Catalogue Identifiers
TIC
TIC 50171060
Gaia DR2
Gaia DR2 6050191241556876672
Gaia DR3
Gaia DR3 6050191241556876672
System
K2-31
Percentile among Gas Giant cohort
Orbit & Habitability
Orbital Dynamics
Year Length
A year here lasts approximately 1.26 Earth days (0.3% of a terrestrial year) on a nearly circular orbit at a mean orbital distance of 0.0220 AU.
Transit Fingerprint
Depth
0.739 %
Duration
0.982 h
Impact parameter b
0.975
Rp / R★
0.135000
Transit midpoint (BJD)
2,457,191.7089
Photometric dip
Transit produces a flux drop of 7,385 ppm lasting ≈ 0.98 h.
Extended Orbital Architecture
Planet / star radius ratio
0.135000
Semi-major axis / stellar radius
6.050
Impact parameter (b)
0.975
RV semi-amplitude (K)
350.900 m/s
Transit mid-time (BJD)
2,457,191.7089
Angular separation (arcsec)
0.19900
Eq. Temperature
1,688K
(1415 °C)
Insolation (S⊕)
1,272.00
Earth = 1.00
Earth Similarity (ESI)
0.033
0 = alien, 1 = Earth-identical
Inside the inner HZ boundary (too hot for liquid water) — the dayside is scorched.
Detection Signatures
Transit photometry
A transit dip has been observed from at least one telescope.
Radial velocity
Stellar wobble has been measured spectroscopically.
Discovery Paper
Primary reference
Dai et al. 2016Instrument
Kepler CCD Array
Publication
2016-06
Observation locale
Space
Discovery cohort
Planets confirmed in 2016 at K2 (12 shown).
Host System: K2-31
Spectral Class
G-type yellow (Sun-like)
Effective Temperature
5,280 K — cooler than the Sun (5,778 K)
Estimated Age
—
Stellar Radius
0.780 R☉
Stellar Mass
0.910 M☉
Metallicity [Fe/H]
0.08
Extended Stellar Properties
Surface gravity (log g)
4.600 dex
Stellar density
1.193 g/cm³
Systemic radial velocity
-4.75 km/s
Rotational v·sin i
2.60 km/s
Rotation period
18.38 days
Activity index (log R'HK)
-4.647
Metallicity ratio
[Fe/H]
Multi-band Host Photometry — 12 bands
Astrometric Data
Parallax
9.019 mas
Total Proper Motion
104.395 mas/yr
PM Right Ascension
-40.23 mas/yr
PM Declination
-96.33 mas/yr
Galactic Cartesian (pc)
x = -0.381 · y = -0.834 · z = -0.400
Equatorial (J2000)
RA 245.44055° · Dec -23.54827°
Galactic ℓ, b
352.995° · 18.275°
Ecliptic λ, β
247.585° · -2.000°
HTM-20 index
484654301
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