Key parameters at a glance
- A radius of 1.97 Earth radii
- A mass of 4.54 Earth masses
- Surface gravity around 1.17 g
- An orbital period of 6.102 days
- Semi-major axis 0.0590 AU
- Distance from Earth 822.95 light-years
- Earth Similarity Index 0.791
- Travel time at Voyager 1 speed 14,512,728 years
- Almost certainly tidally locked to its host star given the close orbit
K2-81 b Planet Profile
Physical Specs
Classification
Planet Type
Super-Earth
Discovery
Size rank in cohort
Rank by radius
#38of 1176
top 3.1%
This planet
1.97R⊕
Super-Earth median
1.60R⊕
Nearest-size peers
| Metric | Earth | K2-81 b | Jupiter |
|---|---|---|---|
| Radius (R⊕) | 1.00 | 1.97 | 11.21 |
| Mass (M⊕) | 1.00 | 4.54 | 317.83 |
| Density (g/cm³) | 5.51 | 3.26 | 1.33 |
| Surface Gravity (g) | 1.00 | 1.17 | 2.53 |
| Insolation (S⊕) | 1.00 | 62.90 | 0.037 |
Star Catalogue Identifiers
TIC
TIC 59040029
Gaia DR2
Gaia DR2 39738656627501056
Gaia DR3
Gaia DR3 39738656627501056
System
K2-81
Percentile among Super-Earth cohort
Orbit & Habitability
Orbital Dynamics
Year Length
A year here lasts approximately 6.10 Earth days (1.7% of a terrestrial year) on a nearly circular orbit at a mean orbital distance of 0.0590 AU.
Transit Fingerprint
Depth
0.108 %
Duration
2.150 h
Rp / R★
0.028504
Transit midpoint (BJD)
2,457,070.4400
Photometric dip
Transit produces a flux drop of 1,076 ppm lasting ≈ 2.15 h.
Extended Orbital Architecture
Planet / star radius ratio
0.028504
Semi-major axis / stellar radius
19.770
Transit mid-time (BJD)
2,457,070.4400
Long. of periastron (ω)
-27.89°
Angular separation (arcsec)
0.23400
Eq. Temperature
—
Insolation (S⊕)
62.90
Earth = 1.00
Earth Similarity (ESI)
0.791
0 = alien, 1 = Earth-identical
Inside the inner HZ boundary (too hot for liquid 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: K2-81
Spectral Class
K-type orange
Effective Temperature
4,674 K — cooler than the Sun (5,778 K)
Estimated Age
—
Stellar Radius
0.635 R☉
Stellar Mass
0.745 M☉
Metallicity [Fe/H]
—
Multi-band Host Photometry — 12 bands
Astrometric Data
Parallax
3.935 mas
Total Proper Motion
36.862 mas/yr
PM Right Ascension
-8.09 mas/yr
PM Declination
-35.96 mas/yr
Galactic Cartesian (pc)
x = 0.520 · y = 0.816 · z = 0.250
Equatorial (J2000)
RA 57.48546° · Dec 14.50206°
Galactic ℓ, b
174.635° · -29.937°
Ecliptic λ, β
58.479° · -5.451°
HTM-20 index
-88477613
Similar Worlds
K2-126 b
Super-Earth · K-type orange
Radius 1.97 R⊕ · 335.8 ly
Kepler-224 e
Super-Earth · K-type orange
Radius 1.97 R⊕ · 2,550.8 ly
Kepler-1816 b
Super-Earth · K-type orange
Radius 1.97 R⊕ · 1,428.0 ly
Kepler-174 b
Super-Earth · K-type orange
Radius 1.96 R⊕ · 1,254.9 ly
GJ 9827 d
Super-Earth · K-type orange
Radius 1.98 R⊕ · 96.7 ly
Kepler-1460 b
Super-Earth · K-type orange
Radius 1.96 R⊕ · 1,804.4 ly