Key parameters at a glance
- A radius of 2.10 Earth radii
- A mass of 5.06 Earth masses
- Surface gravity around 1.15 g
- An orbital period of 10.003 days
- Semi-major axis 0.0780 AU
- Equilibrium temperature 563 K (290 °C)
- Distance from Earth 756.12 light-years
- Earth Similarity Index 0.476
- Travel time at Voyager 1 speed 13,334,192 years
- Almost certainly tidally locked to its host star given the close orbit
K2-4 b Planet Profile
Physical Specs
Classification
Planet Type
Sub-Neptune
Discovery
Size rank in cohort
Rank by radius
#1818of 1978
top 91.9%
This planet
2.10R⊕
Sub-Neptune median
2.71R⊕
Nearest-size peers
| Metric | Earth | K2-4 b | Jupiter |
|---|---|---|---|
| Radius (R⊕) | 1.00 | 2.10 | 11.21 |
| Mass (M⊕) | 1.00 | 5.06 | 317.83 |
| Density (g/cm³) | 5.51 | 3.00 | 1.33 |
| Surface Gravity (g) | 1.00 | 1.15 | 2.53 |
| Insolation (S⊕) | 1.00 | 15.60 | 0.037 |
Star Catalogue Identifiers
TIC
TIC 49462779
Gaia DR2
Gaia DR2 3792100950048409344
Gaia DR3
Gaia DR3 3792100950048409344
System
K2-4
Percentile among Sub-Neptune cohort
Orbit & Habitability
Orbital Dynamics
Year Length
A year here lasts approximately 10.00 Earth days (2.7% of a terrestrial year) on a nearly circular orbit at a mean orbital distance of 0.0780 AU.
Transit Fingerprint
Depth
0.148 %
Duration
2.923 h
Impact parameter b
0.410
Rp / R★
0.033752
Transit midpoint (BJD)
2,456,815.5240
Photometric dip
Transit produces a flux drop of 1,482 ppm lasting ≈ 2.92 h.
Extended Orbital Architecture
Planet / star radius ratio
0.033752
Semi-major axis / stellar radius
27.680
Impact parameter (b)
0.410
Transit mid-time (BJD)
2,456,815.5240
Long. of periastron (ω)
-41.44°
Angular separation (arcsec)
0.33600
Eq. Temperature
563K
(290 °C)
Insolation (S⊕)
15.60
Earth = 1.00
Earth Similarity (ESI)
0.476
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
Montet et al. 2015Instrument
Kepler CCD Array
Publication
2015-08
Observation locale
Space
Discovery cohort
Planets confirmed in 2015 at K2 (12 shown).
Host System: K2-4
Spectral Class
K-type orange
Effective Temperature
4,015 K — cooler than the Sun (5,778 K)
Estimated Age
—
Stellar Radius
0.569 R☉
Stellar Mass
0.635 M☉
Metallicity [Fe/H]
-0.12
Extended Stellar Properties
Surface gravity (log g)
4.849 dex
Stellar density
2.815 g/cm³
Metallicity ratio
[Fe/H]
Multi-band Host Photometry — 17 bands
Astrometric Data
Parallax
4.285 mas
Total Proper Motion
23.998 mas/yr
PM Right Ascension
-23.95 mas/yr
PM Declination
-1.45 mas/yr
Galactic Cartesian (pc)
x = -0.993 · y = 0.091 · z = -0.068
Equatorial (J2000)
RA 174.74554° · Dec -3.90557°
Galactic ℓ, b
270.755° · 54.376°
Ecliptic λ, β
176.728° · -5.672°
HTM-20 index
747488225
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