Key parameters at a glance
- A radius of 7.50 Earth radii
- A mass of 37.10 Earth masses
- Surface gravity around 0.66 g
- An orbital period of 19.895 days
- Semi-major axis 0.1461 AU
- Equilibrium temperature 787 K (514 °C)
- Distance from Earth 1,277.02 light-years
- Earth Similarity Index 0.192
- Travel time at Voyager 1 speed 22,520,271 years
K2-280 b Planet Profile
Physical Specs
Classification
Planet Type
Neptune-like
Discovery
Size rank in cohort
Rank by radius
#178of 574
top 30.8%
This planet
7.50R⊕
Neptune-like median
6.39R⊕
Nearest-size peers
| Metric | Earth | K2-280 b | Jupiter |
|---|---|---|---|
| Radius (R⊕) | 1.00 | 7.50 | 11.21 |
| Mass (M⊕) | 1.00 | 37.10 | 317.83 |
| Density (g/cm³) | 5.51 | 0.48 | 1.33 |
| Surface Gravity (g) | 1.00 | 0.66 | 2.53 |
| Insolation (S⊕) | 1.00 | 69.50 | 0.037 |
Alternative Mass Estimates
| Method | Value | Interpretation |
|---|---|---|
| Best measured mass | 37.100 M⊕ | Direct mass measurement (not derived). |
Star Catalogue Identifiers
TIC
TIC 119605900
Gaia DR2
Gaia DR2 6772454416893148928
Gaia DR3
Gaia DR3 6772454416893148928
System
K2-280
Percentile among Neptune-like cohort
Orbit & Habitability
Orbital Dynamics
Year Length
A year here lasts approximately 19.90 Earth days (5.4% of a terrestrial year) on a highly eccentric trajectory at a mean orbital distance of 0.1461 AU.
Transit Fingerprint
Depth
0.346 %
Duration
8.267 h
Impact parameter b
0.270
Rp / R★
0.053540
Transit midpoint (BJD)
2,457,307.5811
Photometric dip
Transit produces a flux drop of 3,463 ppm lasting ≈ 8.27 h.
Extended Orbital Architecture
Planet / star radius ratio
0.053540
Semi-major axis / stellar radius
25.790
Impact parameter (b)
0.270
RV semi-amplitude (K)
9.180 m/s
Transit mid-time (BJD)
2,457,307.5811
Long. of periastron (ω)
246.77°
Angular separation (arcsec)
0.37300
Eq. Temperature
787K
(514 °C)
Insolation (S⊕)
69.50
Earth = 1.00
Earth Similarity (ESI)
0.192
0 = alien, 1 = Earth-identical
Inside the inner HZ boundary (too hot for liquid water) — the surface is too hot to retain surface water.
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
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: K2-280
Spectral Class
G-type yellow (Sun-like)
Effective Temperature
5,500 K — cooler than the Sun (5,778 K)
Estimated Age
8.96 Gyr — older than the Sun (4.6 Gyr)
Stellar Radius
1.280 R☉
Stellar Mass
1.030 M☉
Metallicity [Fe/H]
0.33
Extended Stellar Properties
Surface gravity (log g)
4.210 dex
Stellar density
0.800 g/cm³
Systemic radial velocity
-0.15 km/s
Rotational v·sin i
3.00 km/s
Activity index (log R'HK)
-5.273
Metallicity ratio
[Fe/H]
Multi-band Host Photometry — 12 bands
Astrometric Data
Parallax
2.527 mas
Total Proper Motion
13.269 mas/yr
PM Right Ascension
4.44 mas/yr
PM Declination
-12.50 mas/yr
Galactic Cartesian (pc)
x = 0.341 · y = -0.861 · z = -0.379
Equatorial (J2000)
RA 291.59536° · Dec -22.24771°
Galactic ℓ, b
16.324° · -17.322°
Ecliptic λ, β
289.913° · -0.289°
HTM-20 index
1535879015
Similar Worlds
K2-24 c
Neptune-like · G-type yellow (Sun-like)
Radius 7.50 R⊕ · 556.3 ly
K2-11 b
Neptune-like · G-type yellow (Sun-like)
Radius 7.55 R⊕ · 1,074.1 ly
HD 199509 b
Neptune-like · G-type yellow (Sun-like)
Radius 7.43 R⊕ · 79.3 ly
HD 134606 d
Neptune-like · G-type yellow (Sun-like)
Radius 7.59 R⊕ · 87.4 ly
55 Cnc f
Neptune-like · G-type yellow (Sun-like)
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K2-87 b
Neptune-like · G-type yellow (Sun-like)
Radius 7.60 R⊕ · 1,602.2 ly