Key parameters at a glance

A radius of 5.22 Earth radii
A mass of 15.20 Earth masses
Surface gravity around 0.56 g
An orbital period of 12.721 days
Semi-major axis 0.1117 AU
Equilibrium temperature 934 K (661 °C)
Distance from Earth 793.37 light-years
Earth Similarity Index 0.182
Travel time at Voyager 1 speed 13,991,100 years

2 siblings around Kepler-25

Kepler-25 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-25 b	Sub-Neptune	2.75	8.70	6.238	1,185	2011
Kepler-25 c this	Neptune-like	5.22	15.20	12.721	934	2011
Kepler-25 d	Gas Giant	10.00	71.90	122.400	—	2014

Kepler-25 c Planet Profile

Physical Specs

Radius

5.22 R⊕

Radius (Jupiter)

0.465 R♃

Mass

15.20 M⊕

Mass (Jupiter)

0.048 M♃

Density

0.59 g/cm³

Surface Gravity

0.56 g (Earth)

Classification

Planet Type

Neptune-like

ESI Score 0.182

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

#356of 574

top 61.8%

This planet

5.22R⊕

Neptune-like median

6.39R⊕

Nearest-size peers

TOI-5238 b 5.22 R⊕ Kepler-418 c 5.22 R⊕ Kepler-562 b 5.21 R⊕

Metric	Earth	Kepler-25 c	Jupiter
Radius (R⊕)	1.00	5.22	11.21
Mass (M⊕)	1.00	15.20	317.83
Density (g/cm³)	5.51	0.59	1.33
Surface Gravity (g)	1.00	0.56	2.53
Insolation (S⊕)	1.00	210.17	0.037

Alternative Mass Estimates

Method	Value	Interpretation
Best measured mass	15.200 M⊕	Direct mass measurement (not derived).
Minimum mass (M sin i)	24.065 M⊕	Lower bound from radial-velocity fitting.

Star Catalogue Identifiers

TIC

TIC 120960812

Gaia DR2

Gaia DR2 2100451630105041152

Gaia DR3

Gaia DR3 2100451630105041152

System

Kepler-25

Percentile among Neptune-like cohort

Radius 5.217 R⊕ · percentile 38 / cohort 574

Mass 15.200 M⊕ · percentile 7 / cohort 574

Orbital period 12.72 d · percentile 42 / cohort 524

Distance 243.25 pc · percentile 43 / cohort 572

ESI 0.182 · percentile 23 / cohort 574

Orbit & Habitability

Orbital Dynamics

Period

12.721 days

Semi-major axis

0.1117 AU

Eccentricity

0.006

Inclination

92.76 °

Year Length

A year here lasts approximately 12.72 Earth days (3.5% of a terrestrial year) on a nearly circular orbit at a mean orbital distance of 0.1117 AU.

Transit Fingerprint

Depth

0.107 %

Duration

2.862 h

Impact parameter b

0.880

Rp / R★

0.036370

Transit midpoint (BJD)

2,455,711.1501

Photometric dip

Transit produces a flux drop of 1,070 ppm lasting ≈ 2.86 h.

Extended Orbital Architecture

Planet / star radius ratio

0.036370

Semi-major axis / stellar radius

18.440

Impact parameter (b)

0.880

RV semi-amplitude (K)

6.013 m/s

Transit mid-time (BJD)

2,455,711.1501

Sky-projected obliquity (λ)

-0.90°

True obliquity (ψ)

26.90°

Angular separation (arcsec)

0.45900

Eq. Temperature

934K

(661 °C)

Insolation (S⊕)

210.17

Earth = 1.00

Earth Similarity (ESI)

0.182

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.

Radial velocity

Stellar wobble has been measured spectroscopically.

Transit timing variations

Gravitational interactions from neighbours have been detected.

Discovery Paper

Primary reference

Steffen et al. 2012

Instrument

Kepler CCD Array

Publication

2012-04

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-25

Spectral Class

F-type yellow-white

Effective Temperature

6,354 K — hotter than the Sun (5,778 K)

Estimated Age

2.75 Gyr — younger than the Sun (4.6 Gyr)

Stellar Radius

1.316 R☉

Stellar Mass

1.165 M☉

Metallicity [Fe/H]

0.11

Extended Stellar Properties

Surface gravity (log g)

4.285 dex

Stellar density

0.750 g/cm³

Systemic radial velocity

-7.59 km/s

Rotational v·sin i

9.34 km/s

Metallicity ratio

[Fe/H]

Distance

243.25 parsec

Light-years 793.37 ly

V-band magnitude

10.77 mag

Voyager-speed travel 13,991,100 yr

Multi-band Host Photometry — 14 bands

Astrometric Data

Parallax

4.082 mas

Total Proper Motion

6.186 mas/yr

PM Right Ascension

-0.45 mas/yr

PM Declination

6.17 mas/yr

Galactic Cartesian (pc)

x = 0.221 · y = -0.739 · z = 0.636

Equatorial (J2000)

RA 286.63839° · Dec 39.48790°

Galactic ℓ, b

70.350° · 14.164°

Ecliptic λ, β

297.442° · 61.351°

HTM-20 index

-747501211