Key parameters at a glance

A radius of 3.58 Earth radii
A mass of 12.50 Earth masses
Surface gravity around 0.98 g
An orbital period of 14.075 days
Distance from Earth 1,245.52 light-years
Earth Similarity Index 0.580
Travel time at Voyager 1 speed 21,964,709 years

K2-217 b Planet Profile

Physical Specs

Radius

3.58 R⊕

Radius (Jupiter)

0.319 R♃

Mass

12.50 M⊕

Mass (Jupiter)

0.039 M♃

Density

1.50 g/cm³

Surface Gravity

0.98 g (Earth)

Classification

Planet Type

Sub-Neptune

ESI Score 0.580

HZ Position Unknown

Controversial No

Discovery

Year 2018

Method Transit

Facility K2

Telescope 0.95 m Kepler Telescope

Size rank in cohort

Rank by radius

#149of 1978

top 7.5%

This planet

3.58R⊕

Sub-Neptune median

2.71R⊕

Nearest-size peers

MOA-2007-BLG-192L b 3.58 R⊕ Kepler-729 b 3.58 R⊕ K2-8 b 3.58 R⊕

Metric	Earth	K2-217 b	Jupiter
Radius (R⊕)	1.00	3.58	11.21
Mass (M⊕)	1.00	12.50	317.83
Density (g/cm³)	5.51	1.50	1.33
Surface Gravity (g)	1.00	0.98	2.53
Insolation (S⊕)	1.00	—	0.037

Star Catalogue Identifiers

TIC

TIC 405333767

Gaia DR2

Gaia DR2 2556248536102683008

Gaia DR3

Gaia DR3 2556248536102683008

System

K2-217

Percentile among Sub-Neptune cohort

Radius 3.579 R⊕ · percentile 92 / cohort 1978

Mass 12.500 M⊕ · percentile 85 / cohort 1978

Orbital period 14.07 d · percentile 48 / cohort 1946

Distance 381.88 pc · percentile 40 / cohort 1975

ESI 0.580 · percentile 80 / cohort 1978

Orbit & Habitability

Orbital Dynamics

Period

14.075 days

Semi-major axis

— AU

Eccentricity

—

Inclination

88.04 °

Year Length

A year here lasts approximately 14.07 Earth days (3.9% of a terrestrial year).

Transit Fingerprint

Depth

0.064 %

Duration

5.688 h

Rp / R★

0.024599

Transit midpoint (BJD)

2,457,395.0045

Photometric dip

Transit produces a flux drop of 636 ppm lasting ≈ 5.69 h.

Eq. Temperature

—

Insolation (S⊕)

—

Earth = 1.00

Earth Similarity (ESI)

0.580

0 = alien, 1 = Earth-identical

Discovery Paper

Primary reference

Mayo et al. 2018

Instrument

Kepler CCD Array

Publication

2018-03

Observation locale

Space

Discovery cohort

Planets confirmed in 2018 at K2 (12 shown).

K2-190 c · Rocky Terrestrial K2-183 b · Rocky Terrestrial K2-209 b · Rocky Terrestrial K2-210 b · Rocky Terrestrial K2-165 b · Super-Earth K2-169 b · Super-Earth K2-148 b · Super-Earth K2-219 b · Super-Earth K2-190 b · Super-Earth K2-200 b · Super-Earth K2-201 b · Super-Earth K2-170 b · Super-Earth

Host System: K2-217

Spectral Class

G-type yellow (Sun-like)

Effective Temperature

5,967 K — hotter than the Sun (5,778 K)

Estimated Age

—

Stellar Radius

1.334 R☉

Stellar Mass

1.103 M☉

Metallicity [Fe/H]

0.04

Extended Stellar Properties

Surface gravity (log g)

4.170 dex

Stellar density

0.775 g/cm³

Systemic radial velocity

-5.95 km/s

Metallicity ratio

[Fe/H]

Distance

381.88 parsec

Light-years 1,245.52 ly

V-band magnitude

12.26 mag

Voyager-speed travel 21,964,709 yr

Multi-band Host Photometry — 17 bands

Astrometric Data

Parallax

2.591 mas

Total Proper Motion

5.097 mas/yr

PM Right Ascension

-4.17 mas/yr

PM Declination

2.93 mas/yr

Galactic Cartesian (pc)

x = 0.974 · y = 0.195 · z = 0.113

Equatorial (J2000)

RA 11.29837° · Dec 6.48159°

Galactic ℓ, b

120.131° · -56.356°

Ecliptic λ, β

12.916° · 1.498°

HTM-20 index

-1898819457