Key parameters at a glance

A radius of 2.95 Earth radii
A mass of 9.00 Earth masses
Surface gravity around 1.03 g
An orbital period of 24.160 days
Semi-major axis 0.1344 AU
Distance from Earth 46.69 light-years
Earth Similarity Index 0.646
Travel time at Voyager 1 speed 823,393 years
Almost certainly tidally locked to its host star given the close orbit

GJ 685 b Planet Profile

Physical Specs

Radius

2.95 R⊕

Radius (Jupiter)

0.263 R♃

Mass

9.00 M⊕

Mass (Jupiter)

0.028 M♃

Density

1.93 g/cm³

Surface Gravity

1.03 g (Earth)

Classification

Planet Type

Sub-Neptune

ESI Score 0.646

HZ Position Unknown

Controversial No

Discovery

Year 2019

Method Radial Velocity

Facility Roque de los Muchachos Observatory

Telescope 3.58 m Telescopio Nazionale Galileo

Size rank in cohort

Rank by radius

#557of 1978

top 28.1%

This planet

2.95R⊕

Sub-Neptune median

2.71R⊕

Nearest-size peers

Kepler-344 c 2.95 R⊕ Kepler-1641 c 2.95 R⊕ Kepler-154 c 2.95 R⊕

Metric	Earth	GJ 685 b	Jupiter
Radius (R⊕)	1.00	2.95	11.21
Mass (M⊕)	1.00	9.00	317.83
Density (g/cm³)	5.51	1.93	1.33
Surface Gravity (g)	1.00	1.03	2.53
Insolation (S⊕)	1.00	—	0.037

Alternative Mass Estimates

Method	Value	Interpretation
Minimum mass (M sin i)	9.000 M⊕	Lower bound from radial-velocity fitting.

Star Catalogue Identifiers

HIP

HIP 86087

TIC

TIC 219780306

Gaia DR2

Gaia DR2 1439069444391326208

Gaia DR3

Gaia DR3 1439069444391326208

System

GJ 685

Percentile among Sub-Neptune cohort

Radius 2.950 R⊕ · percentile 71 / cohort 1978

Mass 9.000 M⊕ · percentile 65 / cohort 1978

Orbital period 24.16 d · percentile 68 / cohort 1946

Distance 14.32 pc · percentile 2 / cohort 1975

ESI 0.646 · percentile 87 / cohort 1978

Orbit & Habitability

Orbital Dynamics

Period

24.160 days

Semi-major axis

0.1344 AU

Eccentricity

0.000

Inclination

— °

Year Length

A year here lasts approximately 24.16 Earth days (6.6% of a terrestrial year) on a nearly circular orbit at a mean orbital distance of 0.1344 AU.

Eq. Temperature

—

Insolation (S⊕)

—

Earth = 1.00

Earth Similarity (ESI)

0.646

0 = alien, 1 = Earth-identical

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

Discovery Paper

Primary reference

Pinamonti et al. 2019

Instrument

HARPS-N Spectrograph

Publication

2019-05

Observation locale

Ground

Host System: GJ 685

Spectral Class

M-type red dwarf

Effective Temperature

3,816 K — cooler than the Sun (5,778 K)

Estimated Age

—

Stellar Radius

0.540 R☉

Stellar Mass

0.550 M☉

Metallicity [Fe/H]

-0.15

Extended Stellar Properties

Surface gravity (log g)

4.720 dex

Stellar density

4.447 g/cm³

Systemic radial velocity

-15.72 km/s

Rotational v·sin i

1.33 km/s

Rotation period

18.15 days

Metallicity ratio

[Fe/H]

Distance

14.32 parsec

Light-years 46.69 ly

V-band magnitude

9.98 mag

Voyager-speed travel 823,393 yr

Multi-band Host Photometry — 13 bands

Astrometric Data

Parallax

69.825 mas

Total Proper Motion

577.232 mas/yr

PM Right Ascension

261.90 mas/yr

PM Declination

-514.40 mas/yr

Galactic Cartesian (pc)

x = -0.050 · y = -0.472 · z = 0.880

Equatorial (J2000)

RA 263.89604° · Dec 61.67935°

Galactic ℓ, b

90.758° · 32.589°

Ecliptic λ, β

238.591° · 84.445°

HTM-20 index

1657476426