Key parameters at a glance
- A radius of 3.40 Earth radii
- A mass of 15.40 Earth masses
- Surface gravity around 1.33 g
- An orbital period of 8.267 days
- Semi-major axis 0.0796 AU
- Equilibrium temperature 805 K (532 °C)
- Distance from Earth 645.75 light-years
- Earth Similarity Index 0.292
- Travel time at Voyager 1 speed 11,387,854 years
- Almost certainly tidally locked to its host star given the close orbit
K2-105 b Planet Profile
Physical Specs
Classification
Planet Type
Sub-Neptune
Discovery
Size rank in cohort
Rank by radius
#221of 1978
top 11.1%
This planet
3.40R⊕
Sub-Neptune median
2.71R⊕
Nearest-size peers
| Metric | Earth | K2-105 b | Jupiter |
|---|---|---|---|
| Radius (R⊕) | 1.00 | 3.40 | 11.21 |
| Mass (M⊕) | 1.00 | 15.40 | 317.83 |
| Density (g/cm³) | 5.51 | 2.24 | 1.33 |
| Surface Gravity (g) | 1.00 | 1.33 | 2.53 |
| Insolation (S⊕) | 1.00 | 100.00 | 0.037 |
Alternative Mass Estimates
| Method | Value | Interpretation |
|---|---|---|
| Best measured mass | 15.400 M⊕ | Direct mass measurement (not derived). |
Star Catalogue Identifiers
TIC
TIC 6892385
Gaia DR2
Gaia DR2 651907079835937280
Gaia DR3
Gaia DR3 651907079835937280
System
K2-105
Percentile among Sub-Neptune cohort
Orbit & Habitability
Orbital Dynamics
Year Length
A year here lasts approximately 8.27 Earth days (2.3% of a terrestrial year) on a nearly circular orbit at a mean orbital distance of 0.0796 AU.
Transit Fingerprint
Depth
0.134 %
Duration
3.430 h
Impact parameter b
0.420
Rp / R★
0.033320
Transit midpoint (BJD)
2,457,147.9887
Photometric dip
Transit produces a flux drop of 1,338 ppm lasting ≈ 3.43 h.
Extended Orbital Architecture
Planet / star radius ratio
0.033320
Semi-major axis / stellar radius
17.390
Impact parameter (b)
0.420
RV semi-amplitude (K)
9.400 m/s
Transit mid-time (BJD)
2,457,147.9887
Long. of periastron (ω)
90.00°
Sky-projected obliquity (λ)
-81.00°
Angular separation (arcsec)
0.40200
Eq. Temperature
805K
(532 °C)
Insolation (S⊕)
100.00
Earth = 1.00
Earth Similarity (ESI)
0.292
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
Narita et al. 2017Instrument
Kepler CCD Array
Publication
2017-04
Observation locale
Space
Discovery cohort
Planets confirmed in 2017 at K2 (12 shown).
Host System: K2-105
Spectral Class
K-type orange
Effective Temperature
5,373 K — cooler than the Sun (5,778 K)
Estimated Age
0.60 Gyr — younger than the Sun (4.6 Gyr)
Stellar Radius
0.905 R☉
Stellar Mass
0.940 M☉
Metallicity [Fe/H]
0.22
Extended Stellar Properties
Surface gravity (log g)
4.450 dex
Stellar density
1.729 g/cm³
Systemic radial velocity
-32.26 km/s
Rotational v·sin i
2.70 km/s
Activity index (log R'HK)
-4.843
Metallicity ratio
[Fe/H]
Multi-band Host Photometry — 17 bands
Astrometric Data
Parallax
5.022 mas
Total Proper Motion
8.502 mas/yr
PM Right Ascension
6.96 mas/yr
PM Declination
-4.88 mas/yr
Galactic Cartesian (pc)
x = -0.564 · y = 0.792 · z = 0.233
Equatorial (J2000)
RA 125.42030° · Dec 13.49751°
Galactic ℓ, b
210.533° · 26.005°
Ecliptic λ, β
124.500° · -5.800°
HTM-20 index
140481190
Similar Worlds
GJ 3222 b
Sub-Neptune · K-type orange
Radius 3.40 R⊕ · 59.5 ly
K2-395 c
Sub-Neptune · K-type orange
Radius 3.40 R⊕ · 935.2 ly
Kepler-712 b
Sub-Neptune · K-type orange
Radius 3.41 R⊕ · 2,845.7 ly
Kepler-533 b
Sub-Neptune · K-type orange
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Kepler-357 d
Sub-Neptune · K-type orange
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TOI-5789 e
Sub-Neptune · K-type orange
Radius 3.43 R⊕ · 66.7 ly