Key parameters at a glance

A radius of 2.44 Earth radii
A mass of 30.60 Earth masses
Surface gravity around 5.14 g
An orbital period of 13.727 days
Semi-major axis 0.1170 AU
Equilibrium temperature 1,005 K (732 °C)
Distance from Earth 1,802.98 light-years
Earth Similarity Index 0.231
Travel time at Voyager 1 speed 31,795,618 years

3 siblings around Kepler-338

Kepler-338 b 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
Kepler-338 e	Super-Earth	1.56	8.50	9.341	1,143	2014
Kepler-338 b this	Sub-Neptune	2.44	30.60	13.727	1,005	2014
Kepler-338 c	Sub-Neptune	2.34	6.08	24.311	831	2014
Kepler-338 d	Sub-Neptune	3.00	9.27	44.431	680	2014

Kepler-338 b Planet Profile

Physical Specs

Radius

2.44 R⊕

Radius (Jupiter)

0.218 R♃

Mass

30.60 M⊕

Mass (Jupiter)

0.096 M♃

Density

11.60 g/cm³

Surface Gravity

5.14 g (Earth)

Classification

Planet Type

Sub-Neptune

ESI Score 0.231

HZ Position Inner

Controversial No

Discovery

Year 2014

Method Transit

Facility Kepler

Telescope 0.95 m Kepler Telescope

Size rank in cohort

Rank by radius

#1269of 1978

top 64.1%

This planet

2.44R⊕

Sub-Neptune median

2.71R⊕

Nearest-size peers

HD 106315 b 2.44 R⊕ K2-12 b 2.44 R⊕ Kepler-1086 b 2.44 R⊕

Metric	Earth	Kepler-338 b	Jupiter
Radius (R⊕)	1.00	2.44	11.21
Mass (M⊕)	1.00	30.60	317.83
Density (g/cm³)	5.51	11.60	1.33
Surface Gravity (g)	1.00	5.14	2.53
Insolation (S⊕)	1.00	256.61	0.037

Alternative Mass Estimates

Method	Value	Interpretation
Best measured mass	30.600 M⊕	Direct mass measurement (not derived).

Star Catalogue Identifiers

TIC

TIC 258203303

Gaia DR2

Gaia DR2 2104344141784539264

Gaia DR3

Gaia DR3 2104344141784539264

System

Kepler-338

Percentile among Sub-Neptune cohort

Radius 2.440 R⊕ · percentile 36 / cohort 1978

Mass 30.600 M⊕ · percentile 97 / cohort 1978

Orbital period 13.73 d · percentile 47 / cohort 1946

Distance 552.80 pc · percentile 49 / cohort 1975

ESI 0.231 · percentile 12 / cohort 1978

Orbit & Habitability

Orbital Dynamics

Period

13.727 days

Semi-major axis

0.1170 AU

Eccentricity

0.040

Inclination

89.90 °

Year Length

A year here lasts approximately 13.73 Earth days (3.8% of a terrestrial year) on a nearly circular orbit at a mean orbital distance of 0.1170 AU.

Transit Fingerprint

Depth

0.020 %

Duration

7.288 h

Impact parameter b

0.140

Rp / R★

0.013410

Transit midpoint (BJD)

2,454,971.7483

Photometric dip

Transit produces a flux drop of 199 ppm lasting ≈ 7.29 h.

Extended Orbital Architecture

Planet / star radius ratio

0.013410

Semi-major axis / stellar radius

14.475

Impact parameter (b)

0.140

Transit mid-time (BJD)

2,454,971.7483

Angular separation (arcsec)

0.21200

Eq. Temperature

1,005K

(732 °C)

Insolation (S⊕)

256.61

Earth = 1.00

Earth Similarity (ESI)

0.231

0 = alien, 1 = Earth-identical

Inside the inner HZ boundary (too hot for liquid water) — the dayside is scorched.

Detection Signatures

Transit photometry

A transit dip has been observed from at least one telescope.

Transit timing variations

Gravitational interactions from neighbours have been detected.

Discovery Paper

Primary reference

Rowe et al. 2014

Instrument

Kepler CCD Array

Publication

2014-03

Observation locale

Space

Discovery cohort

Planets confirmed in 2014 at Kepler (12 shown).

Kepler-186 e · Super-Earth Kepler-395 c · Super-Earth Kepler-220 e · Super-Earth Kepler-249 d · Super-Earth Kepler-296 f · Super-Earth Kepler-367 c · Rocky Terrestrial Kepler-296 e · Super-Earth Kepler-155 c · Sub-Neptune Kepler-138 d · Super-Earth Kepler-333 c · Rocky Terrestrial Kepler-331 d · Super-Earth Kepler-267 d · Sub-Neptune

Host System: Kepler-338

Spectral Class

G-type yellow (Sun-like)

Effective Temperature

5,923 K — hotter than the Sun (5,778 K)

Estimated Age

6.46 Gyr — older than the Sun (4.6 Gyr)

Stellar Radius

1.735 R☉

Stellar Mass

1.105 M☉

Metallicity [Fe/H]

-0.03

Extended Stellar Properties

Surface gravity (log g)

4.017 dex

Stellar density

0.210 g/cm³

Systemic radial velocity

-15.36 km/s

Metallicity ratio

[M/H]

Distance

552.80 parsec

Light-years 1,802.98 ly

V-band magnitude

12.19 mag

Voyager-speed travel 31,795,618 yr

Multi-band Host Photometry — 17 bands

Astrometric Data

Parallax

1.780 mas

Total Proper Motion

22.197 mas/yr

PM Right Ascension

16.22 mas/yr

PM Declination

15.15 mas/yr

Galactic Cartesian (pc)

x = 0.170 · y = -0.738 · z = 0.653

Equatorial (J2000)

RA 282.97906° · Dec 40.78442°

Galactic ℓ, b

70.483° · 17.244°

Ecliptic λ, β

292.177° · 63.228°

HTM-20 index

-861789349