Key parameters at a glance
- A radius of 2.31 Earth radii
- A mass of 5.94 Earth masses
- Surface gravity around 1.11 g
- An orbital period of 9.007 days
- Semi-major axis 0.0752 AU
- Equilibrium temperature 636 K (363 °C)
- Distance from Earth 861.75 light-years
- Earth Similarity Index 0.410
- Travel time at Voyager 1 speed 15,196,900 years
- Almost certainly tidally locked to its host star given the close orbit
K2-57 b Planet Profile
Physical Specs
Classification
Planet Type
Sub-Neptune
Discovery
Size rank in cohort
Rank by radius
#1495of 1978
top 75.5%
This planet
2.31R⊕
Sub-Neptune median
2.71R⊕
Nearest-size peers
| Metric | Earth | K2-57 b | Jupiter |
|---|---|---|---|
| Radius (R⊕) | 1.00 | 2.31 | 11.21 |
| Mass (M⊕) | 1.00 | 5.94 | 317.83 |
| Density (g/cm³) | 5.51 | 2.65 | 1.33 |
| Surface Gravity (g) | 1.00 | 1.11 | 2.53 |
| Insolation (S⊕) | 1.00 | 24.10 | 0.037 |
Star Catalogue Identifiers
TIC
TIC 146799150
Gaia DR2
Gaia DR2 2603155390066307456
Gaia DR3
Gaia DR3 2603155390066307456
System
K2-57
Percentile among Sub-Neptune cohort
Orbit & Habitability
Orbital Dynamics
Year Length
A year here lasts approximately 9.01 Earth days (2.5% of a terrestrial year) on a mildly elliptical path at a mean orbital distance of 0.0752 AU.
Transit Fingerprint
Depth
0.099 %
Duration
2.580 h
Impact parameter b
0.390
Rp / R★
0.031500
Transit midpoint (BJD)
2,457,011.3568
Photometric dip
Transit produces a flux drop of 990 ppm lasting ≈ 2.58 h.
Extended Orbital Architecture
Planet / star radius ratio
0.031500
Semi-major axis / stellar radius
24.090
Impact parameter (b)
0.390
Transit mid-time (BJD)
2,457,011.3568
Long. of periastron (ω)
-20.00°
Angular separation (arcsec)
0.28500
Eq. Temperature
636K
(363 °C)
Insolation (S⊕)
24.10
Earth = 1.00
Earth Similarity (ESI)
0.410
0 = alien, 1 = Earth-identical
Inside the inner HZ boundary (too hot for liquid water) — the surface is too hot to retain surface water. Close-orbiting tidally-locked around a cool host.
Discovery Paper
Primary reference
Crossfield et al. 2016Instrument
Kepler CCD Array
Publication
2016-09
Observation locale
Space
Discovery cohort
Planets confirmed in 2016 at K2 (12 shown).
Host System: K2-57
Spectral Class
K-type orange
Effective Temperature
4,413 K — cooler than the Sun (5,778 K)
Estimated Age
6.80 Gyr — older than the Sun (4.6 Gyr)
Stellar Radius
0.671 R☉
Stellar Mass
0.699 M☉
Metallicity [Fe/H]
0.08
Extended Stellar Properties
Surface gravity (log g)
4.629 dex
Stellar density
3.260 g/cm³
Metallicity ratio
[Fe/H]
Multi-band Host Photometry — 12 bands
Astrometric Data
Parallax
3.756 mas
Total Proper Motion
35.050 mas/yr
PM Right Ascension
24.29 mas/yr
PM Declination
-25.27 mas/yr
Galactic Cartesian (pc)
x = 0.926 · y = -0.289 · z = -0.243
Equatorial (J2000)
RA 342.69182° · Dec -14.07000°
Galactic ℓ, b
51.742° · -59.005°
Ecliptic λ, β
338.674° · -6.215°
HTM-20 index
-1116265862
Similar Worlds
Kepler-1798 b
Sub-Neptune · K-type orange
Radius 2.31 R⊕ · 1,289.0 ly
Kepler-417 b
Sub-Neptune · K-type orange
Radius 2.31 R⊕ · 3,176.7 ly
TOI-178 e
Sub-Neptune · K-type orange
Radius 2.30 R⊕ · 204.5 ly
K2-59 c
Sub-Neptune · K-type orange
Radius 2.30 R⊕ · 1,015.4 ly
Kepler-224 d
Sub-Neptune · K-type orange
Radius 2.30 R⊕ · 2,550.8 ly
Kepler-621 b
Sub-Neptune · K-type orange
Radius 2.30 R⊕ · 1,268.7 ly