Key parameters at a glance
- A radius of 1.40 Earth radii
- A mass of 2.55 Earth masses
- Surface gravity around 1.30 g
- An orbital period of 2.588 days
- Semi-major axis 0.0361 AU
- Equilibrium temperature 1,203 K (930 °C)
- Distance from Earth 789.67 light-years
- Earth Similarity Index 0.248
- Travel time at Voyager 1 speed 13,925,760 years
1 sibling around K2-189
K2-189 b 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 |
|---|---|---|---|---|---|---|
| K2-189 b this | Super-Earth | 1.40 | 2.55 | 2.588 | 1,203 | 2018 |
| K2-189 c | Sub-Neptune | 2.31 | 5.95 | 6.679 | 877 | 2018 |
K2-189 b Planet Profile
Physical Specs
Classification
Planet Type
Super-Earth
Discovery
Size rank in cohort
Rank by radius
#920of 1176
top 78.1%
This planet
1.40R⊕
Super-Earth median
1.60R⊕
Nearest-size peers
| Metric | Earth | K2-189 b | Jupiter |
|---|---|---|---|
| Radius (R⊕) | 1.00 | 1.40 | 11.21 |
| Mass (M⊕) | 1.00 | 2.55 | 317.83 |
| Density (g/cm³) | 5.51 | 5.07 | 1.33 |
| Surface Gravity (g) | 1.00 | 1.30 | 2.53 |
| Insolation (S⊕) | 1.00 | 497.00 | 0.037 |
Star Catalogue Identifiers
TIC
TIC 422349881
Gaia DR2
Gaia DR2 3606343094804432128
Gaia DR3
Gaia DR3 3606343094804432128
System
K2-189
Percentile among Super-Earth cohort
Orbit & Habitability
Orbital Dynamics
Year Length
A year here lasts approximately 2.59 Earth days (0.7% of a terrestrial year) at a mean orbital distance of 0.0361 AU.
Transit Fingerprint
Depth
0.030 %
Duration
2.220 h
Impact parameter b
0.410
Rp / R★
0.015900
Transit midpoint (BJD)
2,457,222.1466
Photometric dip
Transit produces a flux drop of 300 ppm lasting ≈ 2.22 h.
Extended Orbital Architecture
Planet / star radius ratio
0.015900
Semi-major axis / stellar radius
7.950
Impact parameter (b)
0.410
Transit mid-time (BJD)
2,457,222.1466
Angular separation (arcsec)
0.14900
Eq. Temperature
1,203K
(930 °C)
Insolation (S⊕)
497.00
Earth = 1.00
Earth Similarity (ESI)
0.248
0 = alien, 1 = Earth-identical
Inside the inner HZ boundary (too hot for liquid water) — the dayside is scorched.
Discovery Paper
Primary reference
Mayo et al. 2018Instrument
Kepler CCD Array
Publication
2018-03
Observation locale
Space
Discovery cohort
Planets confirmed in 2018 at K2 (12 shown).
Host System: K2-189
Spectral Class
G-type yellow (Sun-like)
Effective Temperature
5,442 K — cooler than the Sun (5,778 K)
Estimated Age
—
Stellar Radius
0.879 R☉
Stellar Mass
0.850 M☉
Metallicity [Fe/H]
-0.10
Extended Stellar Properties
Surface gravity (log g)
4.510 dex
Stellar density
2.072 g/cm³
Systemic radial velocity
15.96 km/s
Rotational v·sin i
1.90 km/s
Activity index (log R'HK)
-4.999
Metallicity ratio
[Fe/H]
Multi-band Host Photometry — 12 bands
Astrometric Data
Parallax
4.102 mas
Total Proper Motion
60.231 mas/yr
PM Right Ascension
28.42 mas/yr
PM Declination
-53.10 mas/yr
Galactic Cartesian (pc)
x = -0.885 · y = -0.387 · z = -0.259
Equatorial (J2000)
RA 203.62144° · Dec -15.03652°
Galactic ℓ, b
318.137° · 46.560°
Ecliptic λ, β
207.375° · -4.824°
HTM-20 index
678412323
Similar Worlds
K2-201 b
Super-Earth · G-type yellow (Sun-like)
Radius 1.40 R⊕ · 645.6 ly
EPIC 206024342 c
Super-Earth · G-type yellow (Sun-like)
Radius 1.40 R⊕ · 1,206.4 ly
K2-187 c
Super-Earth · G-type yellow (Sun-like)
Radius 1.40 R⊕ · 1,079.3 ly
Kepler-770 d
Super-Earth · G-type yellow (Sun-like)
Radius 1.40 R⊕ · 3,034.7 ly
TOI-561 b
Super-Earth · G-type yellow (Sun-like)
Radius 1.40 R⊕ · 279.8 ly
Kepler-1205 b
Super-Earth · G-type yellow (Sun-like)
Radius 1.41 R⊕ · 2,278.2 ly