Key parameters at a glance

A radius of 2.40 Earth radii
A mass of 6.35 Earth masses
Surface gravity around 1.10 g
An orbital period of 7.150 days
Semi-major axis 0.0720 AU
Equilibrium temperature 865 K (592 °C)
Distance from Earth 1,079.30 light-years
Earth Similarity Index 0.296
Travel time at Voyager 1 speed 19,033,497 years

3 siblings around K2-187

K2-187 d shares its host star with 3 other confirmed planets. Side-by-side measurements below.

Planet	Type	Radius (R⊕)	Mass (M⊕)	Period (d)	Eq. T (K)	Year
K2-187 b	Rocky Terrestrial	1.20	1.87	0.774	1,815	2018
K2-187 c	Super-Earth	1.40	2.54	2.872	1,173	2018
K2-187 d this	Sub-Neptune	2.40	6.35	7.150	865	2018
K2-187 e	Super-Earth	1.90	4.27	13.607	698	2018

K2-187 d Planet Profile

Physical Specs

Radius

2.40 R⊕

Radius (Jupiter)

0.214 R♃

Mass

6.35 M⊕

Mass (Jupiter)

0.020 M♃

Density

2.52 g/cm³

Surface Gravity

1.10 g (Earth)

Classification

Planet Type

Sub-Neptune

ESI Score 0.296

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

#1333of 1978

top 67.3%

This planet

2.40R⊕

Sub-Neptune median

2.71R⊕

Nearest-size peers

Kepler-194 d 2.40 R⊕ KIC 8540376 c 2.40 R⊕ Kepler-112 c 2.40 R⊕

Metric	Earth	K2-187 d	Jupiter
Radius (R⊕)	1.00	2.40	11.21
Mass (M⊕)	1.00	6.35	317.83
Density (g/cm³)	5.51	2.52	1.33
Surface Gravity (g)	1.00	1.10	2.53
Insolation (S⊕)	1.00	—	0.037

Star Catalogue Identifiers

TIC

TIC 332024125

Gaia DR2

Gaia DR2 689268759823937280

Gaia DR3

Gaia DR3 689268759823937280

System

K2-187

Percentile among Sub-Neptune cohort

Radius 2.400 R⊕ · percentile 32 / cohort 1978

Mass 6.350 M⊕ · percentile 31 / cohort 1978

Orbital period 7.15 d · percentile 23 / cohort 1946

Distance 330.92 pc · percentile 37 / cohort 1975

ESI 0.296 · percentile 27 / cohort 1978

Orbit & Habitability

Orbital Dynamics

Period

7.150 days

Semi-major axis

0.0720 AU

Eccentricity

—

Inclination

90.30 °

Year Length

A year here lasts approximately 7.15 Earth days (2.0% of a terrestrial year) at a mean orbital distance of 0.0720 AU.

Transit Fingerprint

Depth

0.122 %

Duration

2.839 h

Impact parameter b

0.410

Rp / R★

0.025900

Transit midpoint (BJD)

2,457,203.5209

Photometric dip

Transit produces a flux drop of 1,224 ppm lasting ≈ 2.84 h.

Extended Orbital Architecture

Planet / star radius ratio

0.025900

Semi-major axis / stellar radius

18.000

Impact parameter (b)

0.410

Transit mid-time (BJD)

2,457,203.5209

Angular separation (arcsec)

0.21800

Eq. Temperature

865K

(592 °C)

Insolation (S⊕)

—

Earth = 1.00

Earth Similarity (ESI)

0.296

0 = alien, 1 = Earth-identical

Insufficient insolation data — the surface is too hot to retain surface water.

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: K2-187

Spectral Class

G-type yellow (Sun-like)

Effective Temperature

5,438 K — cooler than the Sun (5,778 K)

Estimated Age

—

Stellar Radius

0.830 R☉

Stellar Mass

0.967 M☉

Metallicity [Fe/H]

0.00

Extended Stellar Properties

Surface gravity (log g)

4.600 dex

Stellar density

1.682 g/cm³

Metallicity ratio

[Fe/H]

Distance

330.92 parsec

Light-years 1,079.30 ly

V-band magnitude

13.10 mag

Voyager-speed travel 19,033,497 yr

Multi-band Host Photometry — 17 bands

Astrometric Data

Parallax

2.994 mas

Total Proper Motion

32.914 mas/yr

PM Right Ascension

-11.86 mas/yr

PM Declination

-30.70 mas/yr

Galactic Cartesian (pc)

x = -0.621 · y = 0.677 · z = 0.394

Equatorial (J2000)

RA 132.52356° · Dec 23.19247°

Galactic ℓ, b

202.777° · 35.764°

Ecliptic λ, β

128.598° · 5.270°

HTM-20 index

800566993