Key parameters at a glance

A radius of 2.52 Earth radii
A mass of 43.00 Earth masses
Surface gravity around 6.77 g
An orbital period of 82.200 days
Semi-major axis 0.3900 AU
Equilibrium temperature 525 K (252 °C)
Distance from Earth 1,333.47 light-years
Earth Similarity Index 0.411
Travel time at Voyager 1 speed 23,515,786 years

2 siblings around Kepler-129

Kepler-129 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-129 b	Sub-Neptune	2.40	20.00	15.790	910	2014
Kepler-129 c this	Sub-Neptune	2.52	43.00	82.200	525	2014
Kepler-129 d	Gas Giant	12.60	2,637.98	2,646.000	—	2021

Kepler-129 c Planet Profile

Physical Specs

Radius

2.52 R⊕

Radius (Jupiter)

0.225 R♃

Mass

43.00 M⊕

Mass (Jupiter)

0.135 M♃

Density

14.80 g/cm³

Surface Gravity

6.77 g (Earth)

Classification

Planet Type

Sub-Neptune

ESI Score 0.411

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

#1147of 1978

top 57.9%

This planet

2.52R⊕

Sub-Neptune median

2.71R⊕

Nearest-size peers

Kepler-748 b 2.52 R⊕ TOI-1749 d 2.52 R⊕ Kepler-361 c 2.52 R⊕

Metric	Earth	Kepler-129 c	Jupiter
Radius (R⊕)	1.00	2.52	11.21
Mass (M⊕)	1.00	43.00	317.83
Density (g/cm³)	5.51	14.80	1.33
Surface Gravity (g)	1.00	6.77	2.53
Insolation (S⊕)	1.00	17.55	0.037

Alternative Mass Estimates

Method	Value	Interpretation
Best measured mass	43.000 M⊕	Direct mass measurement (not derived).
Minimum mass (M sin i)	25.314 M⊕	Lower bound from radial-velocity fitting.

Star Catalogue Identifiers

TIC

TIC 164999822

Gaia DR2

Gaia DR2 2131494313689868416

Gaia DR3

Gaia DR3 2131494313689868416

System

Kepler-129

Percentile among Sub-Neptune cohort

Radius 2.520 R⊕ · percentile 42 / cohort 1978

Mass 43.000 M⊕ · percentile 97 / cohort 1978

Orbital period 82.20 d · percentile 92 / cohort 1946

Distance 408.85 pc · percentile 42 / cohort 1975

ESI 0.411 · percentile 55 / cohort 1978

Orbit & Habitability

Orbital Dynamics

Period

82.200 days

Semi-major axis

0.3900 AU

Eccentricity

0.200

Inclination

90.00 °

Year Length

A year here lasts approximately 82.20 Earth days (22.5% of a terrestrial year) on a mildly elliptical path at a mean orbital distance of 0.3900 AU.

Transit Fingerprint

Depth

0.023 %

Duration

10.627 h

Impact parameter b

0.610

Rp / R★

0.013819

Transit midpoint (BJD)

2,455,041.7869

Photometric dip

Transit produces a flux drop of 234 ppm lasting ≈ 10.63 h.

Extended Orbital Architecture

Planet / star radius ratio

0.013819

Semi-major axis / stellar radius

59.910

Impact parameter (b)

0.610

RV semi-amplitude (K)

5.500 m/s

Transit mid-time (BJD)

2,455,041.7869

Angular separation (arcsec)

0.95400

Eq. Temperature

525K

(252 °C)

Insolation (S⊕)

17.55

Earth = 1.00

Earth Similarity (ESI)

0.411

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.

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-129

Spectral Class

G-type yellow (Sun-like)

Effective Temperature

5,770 K — cooler than the Sun (5,778 K)

Estimated Age

6.43 Gyr — older than the Sun (4.6 Gyr)

Stellar Radius

1.653 R☉

Stellar Mass

1.178 M☉

Metallicity [Fe/H]

0.29

Extended Stellar Properties

Surface gravity (log g)

4.080 dex

Stellar density

0.280 g/cm³

Systemic radial velocity

-20.21 km/s

Rotational v·sin i

2.13 km/s

Metallicity ratio

[Fe/H]

Distance

408.85 parsec

Light-years 1,333.47 ly

V-band magnitude

11.81 mag

Voyager-speed travel 23,515,786 yr

Multi-band Host Photometry — 14 bands

Astrometric Data

Parallax

2.417 mas

Total Proper Motion

27.975 mas/yr

PM Right Ascension

-13.26 mas/yr

PM Declination

-24.63 mas/yr

Galactic Cartesian (pc)

x = 0.177 · y = -0.647 · z = 0.741

Equatorial (J2000)

RA 285.31118° · Dec 47.84848°

Galactic ℓ, b

78.035° · 18.210°

Ecliptic λ, β

300.654° · 69.663°

HTM-20 index

-86559688