Key parameters at a glance

A radius of 6.14 Earth radii
A mass of 6.40 Earth masses
Surface gravity around 0.17 g
An orbital period of 191.232 days
Semi-major axis 0.6760 AU
Equilibrium temperature 403 K (130 °C)
Distance from Earth 4,021.18 light-years
Earth Similarity Index 0.295
Travel time at Voyager 1 speed 70,913,458 years

1 sibling around Kepler-87

Kepler-87 c shares its host star with 1 other confirmed planet. Side-by-side measurements below.

Planet	Type	Radius (R⊕)	Mass (M⊕)	Period (d)	Eq. T (K)	Year
Kepler-87 b	Gas Giant	13.49	324.20	114.736	478	2013
Kepler-87 c this	Neptune-like	6.14	6.40	191.232	403	2013

Kepler-87 c Planet Profile

Physical Specs

Radius

6.14 R⊕

Radius (Jupiter)

0.548 R♃

Mass

6.40 M⊕

Mass (Jupiter)

0.020 M♃

Density

0.15 g/cm³

Surface Gravity

0.17 g (Earth)

Classification

Planet Type

Neptune-like

ESI Score 0.295

HZ Position Inner

Controversial No

Discovery

Year 2013

Method Transit

Facility Kepler

Telescope 0.95 m Kepler Telescope

Size rank in cohort

Rank by radius

#270of 574

top 46.9%

This planet

6.14R⊕

Neptune-like median

6.39R⊕

Nearest-size peers

Kepler-696 b 6.14 R⊕ Kepler-450 b 6.14 R⊕ HD 85390 b 6.16 R⊕

Metric	Earth	Kepler-87 c	Jupiter
Radius (R⊕)	1.00	6.14	11.21
Mass (M⊕)	1.00	6.40	317.83
Density (g/cm³)	5.51	0.15	1.33
Surface Gravity (g)	1.00	0.17	2.53
Insolation (S⊕)	1.00	4.66	0.037

Alternative Mass Estimates

Method	Value	Interpretation
Best measured mass	6.400 M⊕	Direct mass measurement (not derived).

Star Catalogue Identifiers

TIC

TIC 273592336

Gaia DR2

Gaia DR2 2086306584816171392

Gaia DR3

Gaia DR3 2086306584816171392

System

Kepler-87

Percentile among Neptune-like cohort

Radius 6.140 R⊕ · percentile 53 / cohort 574

Mass 6.400 M⊕ · percentile 2 / cohort 574

Orbital period 191.23 d · percentile 88 / cohort 524

Distance 1,232.90 pc · percentile 79 / cohort 572

ESI 0.295 · percentile 49 / cohort 574

Orbit & Habitability

Orbital Dynamics

Period

191.232 days

Semi-major axis

0.6760 AU

Eccentricity

0.039

Inclination

89.59 °

Year Length

A year here lasts approximately 191.23 Earth days (52.4% of a terrestrial year) on a nearly circular orbit at a mean orbital distance of 0.6760 AU.

Transit Fingerprint

Depth

0.106 %

Duration

16.942 h

Impact parameter b

0.579

Rp / R★

0.031230

Transit midpoint (BJD)

2,455,119.2203

Photometric dip

Transit produces a flux drop of 1,061 ppm lasting ≈ 16.94 h.

Extended Orbital Architecture

Planet / star radius ratio

0.031230

Semi-major axis / stellar radius

80.700

Impact parameter (b)

0.579

Transit mid-time (BJD)

2,455,119.2203

Long. of periastron (ω)

223.20°

Angular separation (arcsec)

0.54800

Eq. Temperature

403K

(130 °C)

Insolation (S⊕)

4.66

Earth = 1.00

Earth Similarity (ESI)

0.295

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

Ofir et al. 2014

Instrument

Kepler CCD Array

Publication

2014-01

Observation locale

Space

Discovery cohort

Planets confirmed in 2013 at Kepler (12 shown).

Kepler-69 c · Super-Earth Kepler-61 b · Sub-Neptune Kepler-62 e · Super-Earth KOI-351 f · Sub-Neptune Kepler-62 f · Super-Earth KOI-351 e · Sub-Neptune Kepler-1704 b · Gas Giant Kepler-37 d · Sub-Neptune Kepler-282 e · Sub-Neptune KOI-351 h · Gas Giant KOI-351 d · Sub-Neptune Kepler-114 c · Super-Earth

Host System: Kepler-87

Spectral Class

G-type yellow (Sun-like)

Effective Temperature

5,600 K — cooler than the Sun (5,778 K)

Estimated Age

7.50 Gyr — older than the Sun (4.6 Gyr)

Stellar Radius

1.820 R☉

Stellar Mass

1.100 M☉

Metallicity [Fe/H]

-0.17

Extended Stellar Properties

Surface gravity (log g)

3.960 dex

Stellar density

0.385 g/cm³

Systemic radial velocity

-9.35 km/s

Rotational v·sin i

4.30 km/s

Metallicity ratio

[Fe/H]

Distance

1,232.90 parsec

Light-years 4,021.18 ly

V-band magnitude

14.68 mag

Voyager-speed travel 70,913,458 yr

Multi-band Host Photometry — 16 bands

Astrometric Data

Parallax

0.783 mas

Total Proper Motion

4.530 mas/yr

PM Right Ascension

-4.43 mas/yr

PM Declination

-0.93 mas/yr

Galactic Cartesian (pc)

x = 0.320 · y = -0.603 · z = 0.731

Equatorial (J2000)

RA 297.91684° · Dec 46.96511°

Galactic ℓ, b

80.911° · 10.108°

Ecliptic λ, β

320.589° · 65.574°

HTM-20 index

1093666933