Key parameters at a glance
- A radius of 2.19 Earth radii
- A mass of 5.43 Earth masses
- Surface gravity around 1.13 g
- An orbital period of 12.118 days
- Semi-major axis 0.0923 AU
- Equilibrium temperature 551 K (278 °C)
- Distance from Earth 742.90 light-years
- Earth Similarity Index 0.478
- Travel time at Voyager 1 speed 13,101,073 years
- Almost certainly tidally locked to its host star given the close orbit
1 sibling around K2-254
K2-254 c shares its host star with 1 other confirmed planet. Side-by-side measurements below.
| Planet | Type | Radius (R⊕) | Mass (M⊕) | Period (d) | Eq. T (K) | Year |
|---|---|---|---|---|---|---|
| K2-254 b | Super-Earth | 1.63 | 3.29 | 4.096 | 791 | 2018 |
| K2-254 c this | Sub-Neptune | 2.19 | 5.43 | 12.118 | 551 | 2018 |
K2-254 c Planet Profile
Physical Specs
Classification
Planet Type
Sub-Neptune
Discovery
Size rank in cohort
Rank by radius
#1691of 1978
top 85.4%
This planet
2.19R⊕
Sub-Neptune median
2.71R⊕
Nearest-size peers
| Metric | Earth | K2-254 c | Jupiter |
|---|---|---|---|
| Radius (R⊕) | 1.00 | 2.19 | 11.21 |
| Mass (M⊕) | 1.00 | 5.43 | 317.83 |
| Density (g/cm³) | 5.51 | 2.84 | 1.33 |
| Surface Gravity (g) | 1.00 | 1.13 | 2.53 |
| Insolation (S⊕) | 1.00 | — | 0.037 |
Star Catalogue Identifiers
TIC
TIC 147683165
Gaia DR2
Gaia DR2 3596876269626641664
Gaia DR3
Gaia DR3 3596876269626641664
System
K2-254
Percentile among Sub-Neptune cohort
Orbit & Habitability
Orbital Dynamics
Year Length
A year here lasts approximately 12.12 Earth days (3.3% of a terrestrial year) at a mean orbital distance of 0.0923 AU.
Transit Fingerprint
Depth
0.120 %
Duration
2.400 h
Impact parameter b
0.420
Rp / R★
0.029800
Transit midpoint (BJD)
2,457,590.6136
Photometric dip
Transit produces a flux drop of 1,200 ppm lasting ≈ 2.40 h.
Extended Orbital Architecture
Planet / star radius ratio
0.029800
Semi-major axis / stellar radius
31.300
Impact parameter (b)
0.420
Transit mid-time (BJD)
2,457,590.6136
Angular separation (arcsec)
0.40500
Eq. Temperature
551K
(278 °C)
Insolation (S⊕)
—
Earth = 1.00
Earth Similarity (ESI)
0.478
0 = alien, 1 = Earth-identical
Insufficient insolation data — the surface is too hot to retain surface water. Close-orbiting tidally-locked around a cool host.
Discovery Paper
Primary reference
Livingston et al. 2018Instrument
Kepler CCD Array
Publication
2018-08
Observation locale
Space
Discovery cohort
Planets confirmed in 2018 at K2 (12 shown).
Host System: K2-254
Spectral Class
K-type orange
Effective Temperature
4,629 K — cooler than the Sun (5,778 K)
Estimated Age
—
Stellar Radius
0.670 R☉
Stellar Mass
0.710 M☉
Metallicity [Fe/H]
-0.14
Extended Stellar Properties
Surface gravity (log g)
4.640 dex
Stellar density
2.711 g/cm³
Metallicity ratio
[Fe/H]
Multi-band Host Photometry — 12 bands
Astrometric Data
Parallax
4.362 mas
Total Proper Motion
13.864 mas/yr
PM Right Ascension
6.59 mas/yr
PM Declination
-12.20 mas/yr
Galactic Cartesian (pc)
x = -0.992 · y = -0.096 · z = -0.082
Equatorial (J2000)
RA 185.55079° · Dec -4.71729°
Galactic ℓ, b
289.329° · 57.380°
Ecliptic λ, β
186.960° · -2.127°
HTM-20 index
106558051
Similar Worlds
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Kepler-1042 b
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Kepler-174 d
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K2-247 c
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