Key parameters at a glance
- A radius of 8.18 Earth radii
- A mass of 50.90 Earth masses
- Surface gravity around 0.76 g
- An orbital period of 8.688 days
- Semi-major axis 0.0773 AU
- Equilibrium temperature 665 K (392 °C)
- Distance from Earth 1,494.25 light-years
- Earth Similarity Index 0.225
- Travel time at Voyager 1 speed 26,351,059 years
- Almost certainly tidally locked to its host star given the close orbit
K2-281 b Planet Profile
Physical Specs
Classification
Planet Type
Neptune-like
Discovery
Size rank in cohort
Rank by radius
#144of 574
top 24.9%
This planet
8.18R⊕
Neptune-like median
6.39R⊕
Nearest-size peers
| Metric | Earth | K2-281 b | Jupiter |
|---|---|---|---|
| Radius (R⊕) | 1.00 | 8.18 | 11.21 |
| Mass (M⊕) | 1.00 | 50.90 | 317.83 |
| Density (g/cm³) | 5.51 | 0.51 | 1.33 |
| Surface Gravity (g) | 1.00 | 0.76 | 2.53 |
| Insolation (S⊕) | 1.00 | — | 0.037 |
Star Catalogue Identifiers
TIC
TIC 380884458
Gaia DR2
Gaia DR2 2577432178095422976
Gaia DR3
Gaia DR3 2577432178095422976
System
K2-281
Percentile among Neptune-like cohort
Orbit & Habitability
Orbital Dynamics
Year Length
A year here lasts approximately 8.69 Earth days (2.4% of a terrestrial year) at a mean orbital distance of 0.0773 AU.
Transit Fingerprint
Depth
1.239 %
Duration
2.750 h
Impact parameter b
0.230
Rp / R★
0.098700
Transit midpoint (BJD)
2,457,393.8821
Photometric dip
Transit produces a flux drop of 12,388 ppm lasting ≈ 2.75 h.
Extended Orbital Architecture
Planet / star radius ratio
0.098700
Semi-major axis / stellar radius
25.900
Impact parameter (b)
0.230
Transit mid-time (BJD)
2,457,393.8821
Angular separation (arcsec)
0.16900
Eq. Temperature
665K
(392 °C)
Insolation (S⊕)
—
Earth = 1.00
Earth Similarity (ESI)
0.225
0 = alien, 1 = Earth-identical
Insufficient insolation data — the surface is too hot to retain surface water. Close-orbiting tidally-locked around a cool host.
Discovery Paper
Primary reference
Livingston et al. 2018Instrument
Kepler CCD Array
Publication
2018-12
Observation locale
Space
Discovery cohort
Planets confirmed in 2018 at K2 (12 shown).
Host System: K2-281
Spectral Class
K-type orange
Effective Temperature
4,812 K — cooler than the Sun (5,778 K)
Estimated Age
—
Stellar Radius
0.760 R☉
Stellar Mass
0.820 M☉
Metallicity [Fe/H]
0.22
Extended Stellar Properties
Surface gravity (log g)
4.590 dex
Stellar density
4.354 g/cm³
Metallicity ratio
[Fe/H]
Multi-band Host Photometry — 17 bands
Astrometric Data
Parallax
2.154 mas
Total Proper Motion
22.723 mas/yr
PM Right Ascension
22.70 mas/yr
PM Declination
0.98 mas/yr
Galactic Cartesian (pc)
x = 0.952 · y = 0.277 · z = 0.127
Equatorial (J2000)
RA 16.22747° · Dec 7.26922°
Galactic ℓ, b
128.830° · -55.448°
Ecliptic λ, β
17.734° · 0.334°
HTM-20 index
1972060006
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