Key parameters at a glance

A radius of 3.90 Earth radii
A mass of 14.50 Earth masses
Surface gravity around 0.95 g
An orbital period of 6.339 days
Equilibrium temperature 874 K (601 °C)
Distance from Earth 947.47 light-years
Earth Similarity Index 0.241
Travel time at Voyager 1 speed 16,708,577 years

K2-388 b Planet Profile

Physical Specs

Radius

3.90 R⊕

Radius (Jupiter)

0.348 R♃

Mass

14.50 M⊕

Mass (Jupiter)

0.046 M♃

Density

1.34 g/cm³

Surface Gravity

0.95 g (Earth)

Classification

Planet Type

Sub-Neptune

ESI Score 0.241

HZ Position Inner

Controversial No

Discovery

Year 2022

Method Transit

Facility K2

Telescope 0.95 m Kepler Telescope

Size rank in cohort

Rank by radius

#23of 1978

top 1.1%

This planet

3.90R⊕

Sub-Neptune median

2.71R⊕

Nearest-size peers

Kepler-31 d 3.90 R⊕ K2-63 c 3.90 R⊕ Kepler-30 b 3.90 R⊕

Metric	Earth	K2-388 b	Jupiter
Radius (R⊕)	1.00	3.90	11.21
Mass (M⊕)	1.00	14.50	317.83
Density (g/cm³)	5.51	1.34	1.33
Surface Gravity (g)	1.00	0.95	2.53
Insolation (S⊕)	1.00	138.00	0.037

Star Catalogue Identifiers

TIC

TIC 49735922

Gaia DR2

Gaia DR2 2433621314222365312

Gaia DR3

Gaia DR3 2433621314222365312

System

K2-388

Percentile among Sub-Neptune cohort

Radius 3.900 R⊕ · percentile 99 / cohort 1978

Mass 14.500 M⊕ · percentile 92 / cohort 1978

Orbital period 6.34 d · percentile 19 / cohort 1946

Distance 290.50 pc · percentile 34 / cohort 1975

ESI 0.241 · percentile 14 / cohort 1978

Orbit & Habitability

Orbital Dynamics

Period

6.339 days

Semi-major axis

— AU

Eccentricity

—

Inclination

— °

Year Length

A year here lasts approximately 6.34 Earth days (1.7% of a terrestrial year).

Transit Fingerprint

Depth

0.174 %

Duration

3.020 h

Impact parameter b

0.388

Rp / R★

0.037400

Transit midpoint (BJD)

2,457,741.7946

Photometric dip

Transit produces a flux drop of 1,739 ppm lasting ≈ 3.02 h.

Extended Orbital Architecture

Planet / star radius ratio

0.037400

Semi-major axis / stellar radius

14.710

Impact parameter (b)

0.388

Transit mid-time (BJD)

2,457,741.7946

Eq. Temperature

874K

(601 °C)

Insolation (S⊕)

138.00

Earth = 1.00

Earth Similarity (ESI)

0.241

0 = alien, 1 = Earth-identical

Inside the inner HZ boundary (too hot for liquid water) — the surface is too hot to retain surface water.

Discovery Paper

Primary reference

Christiansen et al. 2022

Instrument

Kepler CCD Array

Publication

2022-03

Observation locale

Space

Discovery cohort

Planets confirmed in 2022 at K2 (12 shown).

K2-411 b · Rocky Terrestrial K2-381 b · Rocky Terrestrial K2-384 b · Rocky Terrestrial K2-400 b · Rocky Terrestrial K2-384 c · Rocky Terrestrial K2-369 b · Super-Earth K2-407 b · Super-Earth K2-414 b · Rocky Terrestrial K2-368 b · Super-Earth K2-413 c · Rocky Terrestrial K2-384 e · Super-Earth K2-407 c · Super-Earth

Host System: K2-388

Spectral Class

G-type yellow (Sun-like)

Effective Temperature

5,310 K — cooler than the Sun (5,778 K)

Estimated Age

—

Stellar Radius

0.910 R☉

Stellar Mass

0.930 M☉

Metallicity [Fe/H]

0.24

Extended Stellar Properties

Surface gravity (log g)

4.420 dex

Stellar density

1.578 g/cm³

Rotational v·sin i

1.90 km/s

Activity index (log R'HK)

-5.073

Metallicity ratio

[Fe/H]

Distance

290.50 parsec

Light-years 947.47 ly

V-band magnitude

12.86 mag

Voyager-speed travel 16,708,577 yr

Multi-band Host Photometry — 12 bands

Astrometric Data

Parallax

3.414 mas

Total Proper Motion

23.234 mas/yr

PM Right Ascension

0.39 mas/yr

PM Declination

-23.23 mas/yr

Galactic Cartesian (pc)

x = 0.973 · y = -0.124 · z = -0.192

Equatorial (J2000)

RA 352.71393° · Dec -11.07736°

Galactic ℓ, b

69.324° · -65.173°

Ecliptic λ, β

348.917° · -7.283°

HTM-20 index

1245734320