Key parameters at a glance

A radius of 1.01 Earth radii
A mass of 1.01 Earth masses
Surface gravity around 0.99 g
An orbital period of 11.419 days
Semi-major axis 0.0870 AU
Equilibrium temperature 536 K (263 °C)
Distance from Earth 578.45 light-years
Earth Similarity Index 0.605
Travel time at Voyager 1 speed 10,201,035 years
Almost certainly tidally locked to its host star given the close orbit

2 siblings around Kepler-398

Kepler-398 c shares its host star with 2 other confirmed planets. Side-by-side measurements below.

Planet	Type	Radius (R⊕)	Mass (M⊕)	Period (d)	Eq. T (K)	Year
Kepler-398 b	Rocky Terrestrial	0.93	0.75	4.081	755	2014
Kepler-398 d	Rocky Terrestrial	0.88	0.62	6.834	636	2016
Kepler-398 c this	Rocky Terrestrial	1.01	1.01	11.419	536	2014

Kepler-398 c Planet Profile

Physical Specs

Radius

1.01 R⊕

Radius (Jupiter)

0.090 R♃

Mass

1.01 M⊕

Mass (Jupiter)

0.003 M♃

Density

5.39 g/cm³

Surface Gravity

0.99 g (Earth)

Classification

Planet Type

Rocky Terrestrial

ESI Score 0.605

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

#326of 570

top 57.0%

This planet

1.01R⊕

Rocky Terrestrial median

1.01R⊕

Nearest-size peers

Kepler-322 b 1.01 R⊕ Kepler-282 b 1.01 R⊕ Kepler-1278 b 1.01 R⊕

Metric	Earth	Kepler-398 c	Jupiter
Radius (R⊕)	1.00	1.01	11.21
Mass (M⊕)	1.00	1.01	317.83
Density (g/cm³)	5.51	5.39	1.33
Surface Gravity (g)	1.00	0.99	2.53
Insolation (S⊕)	1.00	20.56	0.037

Star Catalogue Identifiers

TIC

TIC 137155210

Gaia DR2

Gaia DR2 2053457644144430848

Gaia DR3

Gaia DR3 2053457644144430848

System

Kepler-398

Percentile among Rocky Terrestrial cohort

Radius 1.010 R⊕ · percentile 42 / cohort 570

Mass 1.010 M⊕ · percentile 37 / cohort 570

Orbital period 11.42 d · percentile 82 / cohort 567

Distance 177.36 pc · percentile 30 / cohort 566

ESI 0.605 · percentile 79 / cohort 570

Orbit & Habitability

Orbital Dynamics

Period

11.419 days

Semi-major axis

0.0870 AU

Eccentricity

0.000

Inclination

85.38 °

Year Length

A year here lasts approximately 11.42 Earth days (3.1% of a terrestrial year) on a nearly circular orbit at a mean orbital distance of 0.0870 AU.

Transit Fingerprint

Depth

0.015 %

Duration

3.342 h

Impact parameter b

0.900

Rp / R★

0.013604

Transit midpoint (BJD)

2,454,975.1177

Photometric dip

Transit produces a flux drop of 154 ppm lasting ≈ 3.34 h.

Extended Orbital Architecture

Planet / star radius ratio

0.013604

Semi-major axis / stellar radius

11.600

Impact parameter (b)

0.900

Transit mid-time (BJD)

2,454,975.1177

Angular separation (arcsec)

0.49100

Eq. Temperature

536K

(263 °C)

Insolation (S⊕)

20.56

Earth = 1.00

Earth Similarity (ESI)

0.605

0 = alien, 1 = Earth-identical

Inside the inner HZ boundary (too hot for liquid water) — the surface is too hot to retain surface water. Close-orbiting tidally-locked around a cool host.

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-398

Spectral Class

K-type orange

Effective Temperature

4,493 K — cooler than the Sun (5,778 K)

Estimated Age

2.34 Gyr — younger than the Sun (4.6 Gyr)

Stellar Radius

0.613 R☉

Stellar Mass

0.649 M☉

Metallicity [Fe/H]

0.05

Extended Stellar Properties

Surface gravity (log g)

4.689 dex

Stellar density

0.378 g/cm³

Metallicity ratio

[M/H]

Distance

177.36 parsec

Light-years 578.45 ly

V-band magnitude

13.50 mag

Voyager-speed travel 10,201,035 yr

Multi-band Host Photometry — 16 bands

Astrometric Data

Parallax

5.610 mas

Total Proper Motion

44.396 mas/yr

PM Right Ascension

30.66 mas/yr

PM Declination

-32.11 mas/yr

Galactic Cartesian (pc)

x = 0.279 · y = -0.709 · z = 0.647

Equatorial (J2000)

RA 291.46885° · Dec 40.34370°

Galactic ℓ, b

72.746° · 11.166°

Ecliptic λ, β

305.346° · 61.174°

HTM-20 index

1642014504