Key parameters at a glance

A radius of 2.75 Earth radii
A mass of 8.70 Earth masses
Surface gravity around 1.15 g
An orbital period of 6.238 days
Semi-major axis 0.0695 AU
Equilibrium temperature 1,185 K (912 °C)
Distance from Earth 793.37 light-years
Earth Similarity Index 0.203
Travel time at Voyager 1 speed 13,991,100 years

2 siblings around Kepler-25

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

Kepler-25 b Planet Profile

Physical Specs

Radius

2.75 R⊕

Radius (Jupiter)

0.245 R♃

Mass

8.70 M⊕

Mass (Jupiter)

0.028 M♃

Density

2.32 g/cm³

Surface Gravity

1.15 g (Earth)

Classification

Planet Type

Sub-Neptune

ESI Score 0.203

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

#812of 1978

top 41.0%

This planet

2.75R⊕

Sub-Neptune median

2.71R⊕

Nearest-size peers

Kepler-1815 b 2.75 R⊕ TOI-1448 b 2.75 R⊕ Kepler-304 d 2.75 R⊕

Metric	Earth	Kepler-25 b	Jupiter
Radius (R⊕)	1.00	2.75	11.21
Mass (M⊕)	1.00	8.70	317.83
Density (g/cm³)	5.51	2.32	1.33
Surface Gravity (g)	1.00	1.15	2.53
Insolation (S⊕)	1.00	542.96	0.037

Alternative Mass Estimates

Method	Value	Interpretation
Best measured mass	8.700 M⊕	Direct mass measurement (not derived).
Minimum mass (M sin i)	10.797 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 Sub-Neptune cohort

Radius 2.748 R⊕ · percentile 59 / cohort 1978

Mass 8.700 M⊕ · percentile 61 / cohort 1978

Orbital period 6.24 d · percentile 18 / cohort 1946

Distance 243.25 pc · percentile 31 / cohort 1975

ESI 0.203 · percentile 7 / cohort 1978

Orbit & Habitability

Orbital Dynamics

Period

6.238 days

Semi-major axis

0.0695 AU

Eccentricity

0.003

Inclination

92.83 °

Year Length

A year here lasts approximately 6.24 Earth days (1.7% of a terrestrial year) on a nearly circular orbit at a mean orbital distance of 0.0695 AU.

Transit Fingerprint

Depth

0.040 %

Duration

3.544 h

Impact parameter b

0.540

Rp / R★

0.019160

Transit midpoint (BJD)

2,455,703.4200

Photometric dip

Transit produces a flux drop of 403 ppm lasting ≈ 3.54 h.

Extended Orbital Architecture

Planet / star radius ratio

0.019160

Semi-major axis / stellar radius

13.780

Impact parameter (b)

0.540

RV semi-amplitude (K)

3.421 m/s

Transit mid-time (BJD)

2,455,703.4200

Angular separation (arcsec)

0.28600

Eq. Temperature

1,185K

(912 °C)

Insolation (S⊕)

542.96

Earth = 1.00

Earth Similarity (ESI)

0.203

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.

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