Key parameters at a glance

A radius of 0.64 Earth radii
A mass of 158.92 Earth masses
Surface gravity around 387.98 g
An orbital period of 0.180 days
Semi-major axis 0.0058 AU
Equilibrium temperature 1,471 K (1198 °C)
Distance from Earth 322.49 light-years
Earth Similarity Index 0.073
Travel time at Voyager 1 speed 5,687,140 years
Almost certainly tidally locked to its host star given the close orbit

K2-137 b Planet Profile

Physical Specs

Radius

0.64 R⊕

Radius (Jupiter)

0.057 R♃

Mass

158.92 M⊕

Mass (Jupiter)

0.500 M♃

Density

— g/cm³

Surface Gravity

387.98 g (Earth)

Classification

Planet Type

Rocky Terrestrial

ESI Score 0.073

HZ Position Unknown

Controversial No

Discovery

Year 2017

Method Transit

Facility K2

Telescope 0.95 m Kepler Telescope

Size rank in cohort

Rank by radius

#542of 570

top 94.9%

This planet

0.64R⊕

Rocky Terrestrial median

1.01R⊕

Nearest-size peers

Kepler-138 b 0.64 R⊕ Kepler-1371 c 0.64 R⊕ Barnard e 0.64 R⊕

Metric	Earth	K2-137 b	Jupiter
Radius (R⊕)	1.00	0.64	11.21
Mass (M⊕)	1.00	158.92	317.83
Density (g/cm³)	5.51	—	1.33
Surface Gravity (g)	1.00	387.98	2.53
Insolation (S⊕)	1.00	—	0.037

Alternative Mass Estimates

Method	Value	Interpretation
Best measured mass	158.915 M⊕	Direct mass measurement (not derived).

Star Catalogue Identifiers

TIC

TIC 98720702

Gaia DR2

Gaia DR2 3583729340372873344

Gaia DR3

Gaia DR3 3583729340372873344

System

K2-137

Percentile among Rocky Terrestrial cohort

Radius 0.640 R⊕ · percentile 5 / cohort 570

Mass 158.915 M⊕ · percentile 99 / cohort 570

Orbital period 0.18 d · percentile 0 / cohort 567

Distance 98.88 pc · percentile 23 / cohort 566

ESI 0.073 · percentile 0 / cohort 570

Orbit & Habitability

Orbital Dynamics

Period

0.180 days

Semi-major axis

0.0058 AU

Eccentricity

0.000

Inclination

93.10 °

Year Length

A year here lasts roughly 4.3 hours long on a nearly circular orbit at a mean orbital distance of 0.0058 AU.

Transit Fingerprint

Duration

0.629 h

Impact parameter b

0.020

Rp / R★

0.020000

Transit midpoint (BJD)

2,457,639.2757

Extended Orbital Architecture

Planet / star radius ratio

0.020000

Semi-major axis / stellar radius

2.100

Impact parameter (b)

0.020

Transit mid-time (BJD)

2,457,639.2757

Angular separation (arcsec)

0.05870

Eq. Temperature

1,471K

(1198 °C)

Insolation (S⊕)

—

Earth = 1.00

Earth Similarity (ESI)

0.073

0 = alien, 1 = Earth-identical

Insufficient insolation data — the dayside is scorched. Close-orbiting tidally-locked around a cool host.

Discovery Paper

Primary reference

Smith et al. 2018

Instrument

Kepler CCD Array

Publication

2018-03

Observation locale

Space

Discovery cohort

Planets confirmed in 2017 at K2 (12 shown).

K2-129 b · Rocky Terrestrial K2-130 b · Super-Earth K2-133 b · Super-Earth K2-128 b · Super-Earth K2-133 c · Super-Earth K2-116 b · Rocky Terrestrial K2-125 b · Sub-Neptune K2-118 b · Sub-Neptune K2-136 d · Super-Earth K2-123 b · Sub-Neptune K2-136 c · Sub-Neptune K2-124 b · Sub-Neptune

Host System: K2-137

Spectral Class

M-type red dwarf

Effective Temperature

3,697 K — cooler than the Sun (5,778 K)

Estimated Age

—

Stellar Radius

0.290 R☉

Stellar Mass

0.463 M☉

Metallicity [Fe/H]

-0.06

Extended Stellar Properties

Surface gravity (log g)

5.000 dex

Stellar density

13.000 g/cm³

Metallicity ratio

[Fe/H]

Distance

98.88 parsec

Light-years 322.49 ly

V-band magnitude

15.94 mag

Voyager-speed travel 5,687,140 yr

Multi-band Host Photometry — 12 bands

Astrometric Data

Parallax

10.085 mas

Total Proper Motion

79.595 mas/yr

PM Right Ascension

-79.53 mas/yr

PM Declination

3.15 mas/yr

Galactic Cartesian (pc)

x = -0.987 · y = -0.119 · z = -0.108

Equatorial (J2000)

RA 186.87043° · Dec -6.19522°

Galactic ℓ, b

292.192° · 56.176°

Ecliptic λ, β

188.753° · -2.964°

HTM-20 index

936660137