Key parameters at a glance
- A radius of 2.23 Earth radii
- A mass of 5.60 Earth masses
- Surface gravity around 1.13 g
- An orbital period of 17.968 days
- Semi-major axis 0.1190 AU
- Equilibrium temperature 487 K (214 °C)
- Distance from Earth 408.04 light-years
- Earth Similarity Index 0.530
- Travel time at Voyager 1 speed 7,195,798 years
- Almost certainly tidally locked to its host star given the close orbit
K2-17 b Planet Profile
Physical Specs
Classification
Planet Type
Sub-Neptune
Discovery
Size rank in cohort
Rank by radius
#1622of 1978
top 82.0%
This planet
2.23R⊕
Sub-Neptune median
2.71R⊕
Nearest-size peers
| Metric | Earth | K2-17 b | Jupiter |
|---|---|---|---|
| Radius (R⊕) | 1.00 | 2.23 | 11.21 |
| Mass (M⊕) | 1.00 | 5.60 | 317.83 |
| Density (g/cm³) | 5.51 | 2.77 | 1.33 |
| Surface Gravity (g) | 1.00 | 1.13 | 2.53 |
| Insolation (S⊕) | 1.00 | 4.91 | 0.037 |
Star Catalogue Identifiers
TIC
TIC 291090078
Gaia DR2
Gaia DR2 3899064464855774592
Gaia DR3
Gaia DR3 3899064464855774592
System
K2-17
Percentile among Sub-Neptune cohort
Orbit & Habitability
Orbital Dynamics
Year Length
A year here lasts approximately 17.97 Earth days (4.9% of a terrestrial year) on a mildly elliptical path at a mean orbital distance of 0.1190 AU.
Transit Fingerprint
Depth
0.099 %
Duration
2.592 h
Impact parameter b
0.610
Rp / R★
0.029808
Transit midpoint (BJD)
2,456,817.9462
Photometric dip
Transit produces a flux drop of 990 ppm lasting ≈ 2.59 h.
Extended Orbital Architecture
Planet / star radius ratio
0.029808
Semi-major axis / stellar radius
39.380
Impact parameter (b)
0.610
Transit mid-time (BJD)
2,456,817.9462
Long. of periastron (ω)
52.06°
Angular separation (arcsec)
0.95100
Eq. Temperature
487K
(214 °C)
Insolation (S⊕)
4.91
Earth = 1.00
Earth Similarity (ESI)
0.530
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.
Discovery Paper
Primary reference
Montet et al. 2015Instrument
Kepler CCD Array
Publication
2015-08
Observation locale
Space
Discovery cohort
Planets confirmed in 2015 at K2 (12 shown).
Host System: K2-17
Spectral Class
K-type orange
Effective Temperature
4,320 K — cooler than the Sun (5,778 K)
Estimated Age
—
Stellar Radius
0.660 R☉
Stellar Mass
0.710 M☉
Metallicity [Fe/H]
0.15
Extended Stellar Properties
Surface gravity (log g)
4.798 dex
Stellar density
2.412 g/cm³
Systemic radial velocity
-10.67 km/s
Metallicity ratio
[Fe/H]
Multi-band Host Photometry — 17 bands
Astrometric Data
Parallax
7.965 mas
Total Proper Motion
28.554 mas/yr
PM Right Ascension
-24.10 mas/yr
PM Declination
15.32 mas/yr
Galactic Cartesian (pc)
x = -0.993 · y = 0.029 · z = 0.112
Equatorial (J2000)
RA 178.32967° · Dec 6.41232°
Galactic ℓ, b
266.619° · 65.102°
Ecliptic λ, β
175.908° · 5.218°
HTM-20 index
-1430831745
Similar Worlds
K2-268 f
Sub-Neptune · K-type orange
Radius 2.23 R⊕ · 1,069.1 ly
TOI-1346 c
Sub-Neptune · K-type orange
Radius 2.23 R⊕ · 376.5 ly
Kepler-1782 b
Sub-Neptune · K-type orange
Radius 2.23 R⊕ · 997.4 ly
Kepler-1753 b
Sub-Neptune · K-type orange
Radius 2.23 R⊕ · 2,308.2 ly
TOI-1453 c
Sub-Neptune · K-type orange
Radius 2.22 R⊕ · 256.8 ly
Kepler-1701 b
Sub-Neptune · K-type orange
Radius 2.22 R⊕ · 1,905.2 ly