Key parameters at a glance

A radius of 2.54 Earth radii
A mass of 6.99 Earth masses
Surface gravity around 1.08 g
An orbital period of 6.514 days
Semi-major axis 0.0494 AU
Equilibrium temperature 416 K (143 °C)
Distance from Earth 356.28 light-years
Earth Similarity Index 0.577
Travel time at Voyager 1 speed 6,283,051 years
Almost certainly tidally locked to its host star given the close orbit

K2-242 b Planet Profile

Physical Specs

Radius

2.54 R⊕

Radius (Jupiter)

0.227 R♃

Mass

6.99 M⊕

Mass (Jupiter)

0.022 M♃

Density

2.34 g/cm³

Surface Gravity

1.08 g (Earth)

Classification

Planet Type

Sub-Neptune

ESI Score 0.577

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

#1117of 1978

top 56.4%

This planet

2.54R⊕

Sub-Neptune median

2.71R⊕

Nearest-size peers

Kepler-1116 b 2.54 R⊕ Kepler-325 c 2.54 R⊕ HD 189567 c 2.54 R⊕

Metric	Earth	K2-242 b	Jupiter
Radius (R⊕)	1.00	2.54	11.21
Mass (M⊕)	1.00	6.99	317.83
Density (g/cm³)	5.51	2.34	1.33
Surface Gravity (g)	1.00	1.08	2.53
Insolation (S⊕)	1.00	—	0.037

Star Catalogue Identifiers

TIC

TIC 152701771

Gaia DR2

Gaia DR2 3595647565382917120

Gaia DR3

Gaia DR3 3595647565382917120

System

K2-242

Percentile among Sub-Neptune cohort

Radius 2.540 R⊕ · percentile 43 / cohort 1978

Mass 6.990 M⊕ · percentile 40 / cohort 1978

Orbital period 6.51 d · percentile 20 / cohort 1946

Distance 109.24 pc · percentile 21 / cohort 1975

ESI 0.577 · percentile 80 / cohort 1978

Orbit & Habitability

Orbital Dynamics

Period

6.514 days

Semi-major axis

0.0494 AU

Eccentricity

—

Inclination

— °

Year Length

A year here lasts approximately 6.51 Earth days (1.8% of a terrestrial year) at a mean orbital distance of 0.0494 AU.

Transit Fingerprint

Depth

0.624 %

Duration

2.000 h

Impact parameter b

0.420

Rp / R★

0.063300

Transit midpoint (BJD)

2,457,586.2400

Photometric dip

Transit produces a flux drop of 6,240 ppm lasting ≈ 2.00 h.

Extended Orbital Architecture

Planet / star radius ratio

0.063300

Semi-major axis / stellar radius

22.100

Impact parameter (b)

0.420

Transit mid-time (BJD)

2,457,586.2400

Angular separation (arcsec)

0.45200

Eq. Temperature

416K

(143 °C)

Insolation (S⊕)

—

Earth = 1.00

Earth Similarity (ESI)

0.577

0 = alien, 1 = Earth-identical

Insufficient insolation data — the surface is too hot to retain surface water. Close-orbiting tidally-locked around a cool host.

Discovery Paper

Primary reference

Livingston et al. 2018

Instrument

Kepler CCD Array

Publication

2018-08

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: K2-242

Spectral Class

M-type red dwarf

Effective Temperature

3,459 K — cooler than the Sun (5,778 K)

Estimated Age

—

Stellar Radius

0.370 R☉

Stellar Mass

0.380 M☉

Metallicity [Fe/H]

-0.01

Extended Stellar Properties

Surface gravity (log g)

4.890 dex

Stellar density

10.342 g/cm³

Metallicity ratio

[Fe/H]

Distance

109.24 parsec

Light-years 356.28 ly

V-band magnitude

16.41 mag

Voyager-speed travel 6,283,051 yr

Multi-band Host Photometry — 12 bands

Astrometric Data

Parallax

9.126 mas

Total Proper Motion

8.314 mas/yr

PM Right Ascension

-6.94 mas/yr

PM Declination

-4.58 mas/yr

Galactic Cartesian (pc)

x = -0.994 · y = 0.003 · z = -0.114

Equatorial (J2000)

RA 179.83584° · Dec -6.51785°

Galactic ℓ, b

280.502° · 54.070°

Ecliptic λ, β

182.448° · -6.043°

HTM-20 index

1235247431