Key parameters at a glance

A radius of 2.50 Earth radii
A mass of 6.80 Earth masses
Surface gravity around 1.09 g
An orbital period of 13.842 days
Distance from Earth 1,047.66 light-years
Earth Similarity Index 0.704
Travel time at Voyager 1 speed 18,475,518 years

K2-231 b Planet Profile

Physical Specs

Radius

2.50 R⊕

Radius (Jupiter)

0.223 R♃

Mass

6.80 M⊕

Mass (Jupiter)

0.021 M♃

Density

2.39 g/cm³

Surface Gravity

1.09 g (Earth)

Classification

Planet Type

Sub-Neptune

ESI Score 0.704

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

#1168of 1978

top 59.0%

This planet

2.50R⊕

Sub-Neptune median

2.71R⊕

Nearest-size peers

Kepler-126 d 2.50 R⊕ Kepler-254 d 2.50 R⊕ GJ 163 c 2.50 R⊕

Metric	Earth	K2-231 b	Jupiter
Radius (R⊕)	1.00	2.50	11.21
Mass (M⊕)	1.00	6.80	317.83
Density (g/cm³)	5.51	2.39	1.33
Surface Gravity (g)	1.00	1.09	2.53
Insolation (S⊕)	1.00	—	0.037

Star Catalogue Identifiers

TIC

TIC 130538732

Gaia DR2

Gaia DR2 4184182737768311296

Gaia DR3

Gaia DR3 4184182737768311296

System

K2-231

Percentile among Sub-Neptune cohort

Radius 2.500 R⊕ · percentile 40 / cohort 1978

Mass 6.800 M⊕ · percentile 37 / cohort 1978

Orbital period 13.84 d · percentile 47 / cohort 1946

Distance 321.22 pc · percentile 36 / cohort 1975

ESI 0.704 · percentile 93 / cohort 1978

Orbit & Habitability

Orbital Dynamics

Period

13.842 days

Semi-major axis

— AU

Eccentricity

—

Inclination

88.60 °

Year Length

A year here lasts approximately 13.84 Earth days (3.8% of a terrestrial year).

Transit Fingerprint

Depth

0.064 %

Duration

2.940 h

Impact parameter b

0.550

Rp / R★

0.023900

Transit midpoint (BJD)

2,457,320.0016

Photometric dip

Transit produces a flux drop of 635 ppm lasting ≈ 2.94 h.

Extended Orbital Architecture

Planet / star radius ratio

0.023900

Semi-major axis / stellar radius

27.000

Impact parameter (b)

0.550

Transit mid-time (BJD)

2,457,320.0016

Eq. Temperature

—

Insolation (S⊕)

—

Earth = 1.00

Earth Similarity (ESI)

0.704

0 = alien, 1 = Earth-identical

Discovery Paper

Primary reference

Curtis et al. 2018

Instrument

Kepler CCD Array

Publication

2018-04

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: K2-231

Spectral Class

G-type yellow (Sun-like)

Effective Temperature

5,695 K — cooler than the Sun (5,778 K)

Estimated Age

3.00 Gyr — younger than the Sun (4.6 Gyr)

Stellar Radius

0.950 R☉

Stellar Mass

1.010 M☉

Metallicity [Fe/H]

0.14

Extended Stellar Properties

Surface gravity (log g)

4.480 dex

Stellar density

1.211 g/cm³

Systemic radial velocity

41.58 km/s

Rotational v·sin i

2.00 km/s

Metallicity ratio

[Fe/H]

Distance

321.22 parsec

Light-years 1,047.66 ly

V-band magnitude

12.77 mag

Voyager-speed travel 18,475,518 yr

Multi-band Host Photometry — 12 bands

Astrometric Data

Parallax

3.085 mas

Total Proper Motion

26.026 mas/yr

PM Right Ascension

-0.94 mas/yr

PM Declination

-26.01 mas/yr

Galactic Cartesian (pc)

x = 0.315 · y = -0.909 · z = -0.272

Equatorial (J2000)

RA 289.09182° · Dec -15.77122°

Galactic ℓ, b

21.454° · -12.528°

Ecliptic λ, β

288.464° · 6.452°

HTM-20 index

-1521527333