Key parameters at a glance
- A radius of 2.47 Earth radii
- A mass of 11.41 Earth masses
- Surface gravity around 1.88 g
- An orbital period of 8.866 days
- Semi-major axis 0.0756 AU
- Equilibrium temperature 798 K (524 °C)
- Distance from Earth 665.02 light-years
- Earth Similarity Index 0.339
- Travel time at Voyager 1 speed 11,727,610 years
- Almost certainly tidally locked to its host star given the close orbit
K2-180 b Planet Profile
Physical Specs
Classification
Planet Type
Sub-Neptune
Discovery
Size rank in cohort
Rank by radius
#1244of 1978
top 62.8%
This planet
2.47R⊕
Sub-Neptune median
2.71R⊕
Nearest-size peers
| Metric | Earth | K2-180 b | Jupiter |
|---|---|---|---|
| Radius (R⊕) | 1.00 | 2.47 | 11.21 |
| Mass (M⊕) | 1.00 | 11.41 | 317.83 |
| Density (g/cm³) | 5.51 | 4.16 | 1.33 |
| Surface Gravity (g) | 1.00 | 1.88 | 2.53 |
| Insolation (S⊕) | 1.00 | 48.30 | 0.037 |
Alternative Mass Estimates
| Method | Value | Interpretation |
|---|---|---|
| Best measured mass | 11.410 M⊕ | Direct mass measurement (not derived). |
Star Catalogue Identifiers
TIC
TIC 366411016
Gaia DR2
Gaia DR2 600750922666388992
Gaia DR3
Gaia DR3 600750922666388992
System
K2-180
Percentile among Sub-Neptune cohort
Orbit & Habitability
Orbital Dynamics
Year Length
A year here lasts approximately 8.87 Earth days (2.4% of a terrestrial year) on a nearly circular orbit at a mean orbital distance of 0.0756 AU.
Transit Fingerprint
Depth
0.099 %
Duration
2.849 h
Impact parameter b
0.330
Rp / R★
0.031410
Transit midpoint (BJD)
2,457,489.1566
Photometric dip
Transit produces a flux drop of 987 ppm lasting ≈ 2.85 h.
Extended Orbital Architecture
Planet / star radius ratio
0.031410
Semi-major axis / stellar radius
22.630
Impact parameter (b)
0.330
RV semi-amplitude (K)
4.360 m/s
Transit mid-time (BJD)
2,457,489.1566
Long. of periastron (ω)
130.00°
Angular separation (arcsec)
0.37100
Eq. Temperature
798K
(524 °C)
Insolation (S⊕)
48.30
Earth = 1.00
Earth Similarity (ESI)
0.339
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
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: K2-180
Spectral Class
K-type orange
Effective Temperature
5,365 K — cooler than the Sun (5,778 K)
Estimated Age
7.50 Gyr — older than the Sun (4.6 Gyr)
Stellar Radius
0.719 R☉
Stellar Mass
0.735 M☉
Metallicity [Fe/H]
-0.58
Extended Stellar Properties
Surface gravity (log g)
4.591 dex
Stellar density
2.790 g/cm³
Systemic radial velocity
-76.86 km/s
Rotational v·sin i
0.10 km/s
Rotation period
15.70 days
Activity index (log R'HK)
-4.916
Metallicity ratio
[Fe/H]
Multi-band Host Photometry — 17 bands
Astrometric Data
Parallax
4.876 mas
Total Proper Motion
131.940 mas/yr
PM Right Ascension
97.10 mas/yr
PM Declination
-89.33 mas/yr
Galactic Cartesian (pc)
x = -0.585 · y = 0.791 · z = 0.178
Equatorial (J2000)
RA 126.46436° · Dec 10.24658°
Galactic ℓ, b
214.289° · 25.582°
Ecliptic λ, β
126.273° · -8.719°
HTM-20 index
964456614
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Sub-Neptune · K-type orange
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