Key parameters at a glance
- A radius of 2.36 Earth radii
- A mass of 10.30 Earth masses
- Surface gravity around 1.84 g
- An orbital period of 24.368 days
- Semi-major axis 0.1516 AU
- Equilibrium temperature 525 K (252 °C)
- Distance from Earth 220.18 light-years
- Earth Similarity Index 0.514
- Travel time at Voyager 1 speed 3,882,795 years
- Almost certainly tidally locked to its host star given the close orbit
2 siblings around K2-233
K2-233 d shares its host star with 2 other confirmed planets. Side-by-side measurements below.
K2-233 d Planet Profile
Physical Specs
Classification
Planet Type
Sub-Neptune
Discovery
Size rank in cohort
Rank by radius
#1393of 1978
top 70.4%
This planet
2.36R⊕
Sub-Neptune median
2.71R⊕
Nearest-size peers
| Metric | Earth | K2-233 d | Jupiter |
|---|---|---|---|
| Radius (R⊕) | 1.00 | 2.36 | 11.21 |
| Mass (M⊕) | 1.00 | 10.30 | 317.83 |
| Density (g/cm³) | 5.51 | 4.30 | 1.33 |
| Surface Gravity (g) | 1.00 | 1.84 | 2.53 |
| Insolation (S⊕) | 1.00 | 12.70 | 0.037 |
Alternative Mass Estimates
| Method | Value | Interpretation |
|---|---|---|
| Best measured mass | 10.300 M⊕ | Direct mass measurement (not derived). |
Star Catalogue Identifiers
TIC
TIC 428820090
Gaia DR2
Gaia DR2 6253186686054822784
Gaia DR3
Gaia DR3 6253186686054822784
System
K2-233
Percentile among Sub-Neptune cohort
Orbit & Habitability
Orbital Dynamics
Year Length
A year here lasts approximately 24.37 Earth days (6.7% of a terrestrial year) on a mildly elliptical path at a mean orbital distance of 0.1516 AU.
Transit Fingerprint
Duration
3.791 h
Impact parameter b
0.280
Rp / R★
0.030510
Transit midpoint (BJD)
2,458,005.5802
Extended Orbital Architecture
Planet / star radius ratio
0.030510
Semi-major axis / stellar radius
45.910
Impact parameter (b)
0.280
RV semi-amplitude (K)
2.720 m/s
Transit mid-time (BJD)
2,458,005.5802
Long. of periastron (ω)
168.00°
Angular separation (arcsec)
2.25000
Eq. Temperature
525K
(252 °C)
Insolation (S⊕)
12.70
Earth = 1.00
Earth Similarity (ESI)
0.514
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.
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
David et al. 2018Instrument
Kepler CCD Array
Publication
2018-05
Observation locale
Space
Discovery cohort
Planets confirmed in 2018 at K2 (12 shown).
Host System: K2-233
Spectral Class
K-type orange
Effective Temperature
4,796 K — cooler than the Sun (5,778 K)
Estimated Age
0.36 Gyr — younger than the Sun (4.6 Gyr)
Stellar Radius
0.710 R☉
Stellar Mass
0.790 M☉
Metallicity [Fe/H]
-0.08
Extended Stellar Properties
Surface gravity (log g)
4.530 dex
Stellar density
3.080 g/cm³
Systemic radial velocity
-9.65 km/s
Rotational v·sin i
4.50 km/s
Rotation period
9.75 days
Metallicity ratio
[Fe/H]
Multi-band Host Photometry — 12 bands
Astrometric Data
Parallax
14.785 mas
Total Proper Motion
36.981 mas/yr
PM Right Ascension
-19.87 mas/yr
PM Declination
-31.19 mas/yr
Galactic Cartesian (pc)
x = -0.597 · y = -0.724 · z = -0.346
Equatorial (J2000)
RA 230.47990° · Dec -20.23180°
Galactic ℓ, b
344.464° · 30.249°
Ecliptic λ, β
233.316° · -1.683°
HTM-20 index
-1997526897
Similar Worlds
TOI-2443 b
Sub-Neptune · K-type orange
Radius 2.36 R⊕ · 78.0 ly
Kepler-1214 b
Sub-Neptune · K-type orange
Radius 2.36 R⊕ · 2,378.4 ly
Kepler-482 b
Sub-Neptune · K-type orange
Radius 2.36 R⊕ · 1,021.1 ly
Kepler-1022 b
Sub-Neptune · K-type orange
Radius 2.36 R⊕ · 1,370.0 ly
TOI-1782.01
Sub-Neptune · K-type orange
Radius 2.37 R⊕ · 310.7 ly
Kepler-1814 b
Sub-Neptune · K-type orange
Radius 2.37 R⊕ · 2,369.0 ly