Key parameters at a glance

A radius of 5.30 Earth radii
A mass of 1,493.70 Earth masses
Surface gravity around 53.18 g
An orbital period of 42.632 days
Semi-major axis 0.2600 AU
Equilibrium temperature 615 K (342 °C)
Distance from Earth 5,429.32 light-years
Earth Similarity Index 0.210
Travel time at Voyager 1 speed 95,746,110 years

2 siblings around Kepler-31

Kepler-31 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-31 b	Neptune-like	5.50	36.74	20.861	781	2011
Kepler-31 c this	Neptune-like	5.30	1,493.70	42.632	615	2011
Kepler-31 d	Sub-Neptune	3.90	2,161.24	87.645	484	2014

Kepler-31 c Planet Profile

Physical Specs

Radius

5.30 R⊕

Radius (Jupiter)

0.473 R♃

Mass

1,493.70 M⊕

Mass (Jupiter)

4.700 M♃

Density

0.73 g/cm³

Surface Gravity

53.18 g (Earth)

Classification

Planet Type

Neptune-like

ESI Score 0.210

HZ Position Inner

Controversial No

Discovery

Year 2011

Method Transit

Facility Kepler

Telescope 0.95 m Kepler Telescope

Size rank in cohort

Rank by radius

#342of 574

top 59.4%

This planet

5.30R⊕

Neptune-like median

6.39R⊕

Nearest-size peers

TOI-3568 b 5.30 R⊕ Kepler-396 c 5.30 R⊕ K2-32 b 5.30 R⊕

Metric	Earth	Kepler-31 c	Jupiter
Radius (R⊕)	1.00	5.30	11.21
Mass (M⊕)	1.00	1,493.70	317.83
Density (g/cm³)	5.51	0.73	1.33
Surface Gravity (g)	1.00	53.18	2.53
Insolation (S⊕)	1.00	35.25	0.037

Alternative Mass Estimates

Method	Value	Interpretation
Best measured mass	1,493.700 M⊕	Direct mass measurement (not derived).

Star Catalogue Identifiers

TIC

TIC 270788519

Gaia DR2

Gaia DR2 2128013019361703936

Gaia DR3

Gaia DR3 2128013019361703936

System

Kepler-31

Percentile among Neptune-like cohort

Radius 5.300 R⊕ · percentile 40 / cohort 574

Mass 1,493.700 M⊕ · percentile 99 / cohort 574

Orbital period 42.63 d · percentile 67 / cohort 524

Distance 1,664.64 pc · percentile 86 / cohort 572

ESI 0.210 · percentile 30 / cohort 574

Orbit & Habitability

Orbital Dynamics

Period

42.632 days

Semi-major axis

0.2600 AU

Eccentricity

0.000

Inclination

89.85 °

Year Length

A year here lasts approximately 42.63 Earth days (11.7% of a terrestrial year) on a nearly circular orbit at a mean orbital distance of 0.2600 AU.

Transit Fingerprint

Depth

0.173 %

Duration

6.024 h

Impact parameter b

0.855

Rp / R★

0.040000

Transit midpoint (BJD)

2,454,974.1910

Photometric dip

Transit produces a flux drop of 1,729 ppm lasting ≈ 6.02 h.

Extended Orbital Architecture

Planet / star radius ratio

0.040000

Semi-major axis / stellar radius

28.700

Impact parameter (b)

0.855

Transit mid-time (BJD)

2,454,974.1910

Angular separation (arcsec)

0.15600

Eq. Temperature

615K

(342 °C)

Insolation (S⊕)

35.25

Earth = 1.00

Earth Similarity (ESI)

0.210

0 = alien, 1 = Earth-identical

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

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

Fabrycky et al. 2012

Instrument

Kepler CCD Array

Publication

2012-05

Observation locale

Space

Discovery cohort

Planets confirmed in 2011 at Kepler (12 shown).

Kepler-22 b · Sub-Neptune Kepler-20 d · Sub-Neptune Kepler-26 c · Sub-Neptune Kepler-19 c · Sub-Neptune Kepler-26 b · Sub-Neptune Kepler-28 c · Super-Earth Kepler-10 c · Sub-Neptune Kepler-20 f · Rocky Terrestrial Kepler-42 d · Rocky Terrestrial Kepler-16 b · Neptune-like Kepler-28 b · Super-Earth Kepler-34 b · Neptune-like

Host System: Kepler-31

Spectral Class

F-type yellow-white

Effective Temperature

6,340 K — hotter than the Sun (5,778 K)

Estimated Age

0.28 Gyr — younger than the Sun (4.6 Gyr)

Stellar Radius

1.220 R☉

Stellar Mass

1.210 M☉

Metallicity [Fe/H]

-0.08

Extended Stellar Properties

Surface gravity (log g)

4.696 dex

Stellar density

0.610 g/cm³

Metallicity ratio

[Fe/H]

Distance

1,664.64 parsec

Light-years 5,429.32 ly

V-band magnitude

15.50 mag

Voyager-speed travel 95,746,110 yr

Multi-band Host Photometry — 16 bands

Astrometric Data

Parallax

0.572 mas

Total Proper Motion

7.414 mas/yr

PM Right Ascension

-1.02 mas/yr

PM Declination

-7.34 mas/yr

Galactic Cartesian (pc)

x = 0.284 · y = -0.636 · z = 0.718

Equatorial (J2000)

RA 294.02302° · Dec 45.85305°

Galactic ℓ, b

78.627° · 11.957°

Ecliptic λ, β

313.549° · 65.699°

HTM-20 index

-1489710077