Key parameters at a glance

A radius of 4.32 Earth radii
A mass of 17.20 Earth masses
Surface gravity around 0.92 g
An orbital period of 38.142 days
Semi-major axis 0.1630 AU
Distance from Earth 14.84 light-years
Earth Similarity Index 0.520
Travel time at Voyager 1 speed 261,670 years
Almost certainly tidally locked to its host star given the close orbit

1 sibling around GJ 687

GJ 687 b 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
GJ 687 b this	Neptune-like	4.32	17.20	38.142	—	2014
GJ 687 c	Neptune-like	4.14	16.00	727.562	—	2020

GJ 687 b Planet Profile

Physical Specs

Radius

4.32 R⊕

Radius (Jupiter)

0.385 R♃

Mass

17.20 M⊕

Mass (Jupiter)

0.054 M♃

Density

1.17 g/cm³

Surface Gravity

0.92 g (Earth)

Classification

Planet Type

Neptune-like

ESI Score 0.520

HZ Position Unknown

Controversial No

Discovery

Year 2014

Method Radial Velocity

Facility Lick Observatory

Telescope 2.4 m Automated Planet Finder Telescope

Size rank in cohort

Rank by radius

#488of 574

top 84.8%

This planet

4.32R⊕

Neptune-like median

6.39R⊕

Nearest-size peers

Kepler-145 c 4.32 R⊕ KOI-94 c 4.32 R⊕ CoRoT-7 d 4.31 R⊕

Metric	Earth	GJ 687 b	Jupiter
Radius (R⊕)	1.00	4.32	11.21
Mass (M⊕)	1.00	17.20	317.83
Density (g/cm³)	5.51	1.17	1.33
Surface Gravity (g)	1.00	0.92	2.53
Insolation (S⊕)	1.00	—	0.037

Alternative Mass Estimates

Method	Value	Interpretation
Minimum mass (M sin i)	17.200 M⊕	Lower bound from radial-velocity fitting.

Star Catalogue Identifiers

HIP

HIP 86162

TIC

TIC 233193964

Gaia DR2

Gaia DR2 1637645127018395776

Gaia DR3

Gaia DR3 1637645127018395776

System

GJ 687

Percentile among Neptune-like cohort

Radius 4.320 R⊕ · percentile 15 / cohort 574

Mass 17.200 M⊕ · percentile 19 / cohort 574

Orbital period 38.14 d · percentile 65 / cohort 524

Distance 4.55 pc · percentile 0 / cohort 572

ESI 0.520 · percentile 94 / cohort 574

Orbit & Habitability

Orbital Dynamics

Period

38.142 days

Semi-major axis

0.1630 AU

Eccentricity

0.170

Inclination

— °

Year Length

A year here lasts approximately 38.14 Earth days (10.4% of a terrestrial year) on a mildly elliptical path at a mean orbital distance of 0.1630 AU.

Extended Orbital Architecture

RV semi-amplitude (K)

6.140 m/s

Transit mid-time (BJD)

2,454,481.0700

Long. of periastron (ω)

117.00°

Angular separation (arcsec)

35.80000

Eq. Temperature

—

Insolation (S⊕)

—

Earth = 1.00

Earth Similarity (ESI)

0.520

0 = alien, 1 = Earth-identical

Insufficient insolation data. Close-orbiting tidally-locked around a cool host.

Discovery Paper

Primary reference

Burt et al. 2014

Instrument

Levy Spectrograph

Publication

2014-07

Observation locale

Ground

Host System: GJ 687

Spectral Class

M-type red dwarf

Effective Temperature

3,413 K — cooler than the Sun (5,778 K)

Estimated Age

—

Stellar Radius

0.418 R☉

Stellar Mass

0.400 M☉

Metallicity [Fe/H]

0.06

Extended Stellar Properties

Surface gravity (log g)

4.859 dex

Stellar density

8.378 g/cm³

Systemic radial velocity

-28.80 km/s

Metallicity ratio

[Fe/H]

Distance

4.55 parsec

Light-years 14.84 ly

V-band magnitude

9.15 mag

Voyager-speed travel 261,670 yr

Multi-band Host Photometry — 12 bands

Astrometric Data

Parallax

219.781 mas

Total Proper Motion

1,309.394 mas/yr

PM Right Ascension

-320.64 mas/yr

PM Declination

-1,269.53 mas/yr

Galactic Cartesian (pc)

x = -0.038 · y = -0.367 · z = 0.929

Equatorial (J2000)

RA 264.10417° · Dec 68.33367°

Galactic ℓ, b

98.596° · 31.966°

Ecliptic λ, β

139.200° · 87.129°

HTM-20 index

1030525514

Observation Record

Photometric series

Stellar spectra

Archive notes