Key parameters at a glance

A radius of 3.92 Earth radii
A mass of 14.60 Earth masses
Surface gravity around 0.95 g
An orbital period of 124.260 days
Semi-major axis 0.3343 AU
Distance from Earth 15.25 light-years
Earth Similarity Index 0.550
Travel time at Voyager 1 speed 268,905 years

3 siblings around GJ 876

GJ 876 e shares its host star with 3 other confirmed planets. Side-by-side measurements below.

Planet	Type	Radius (R⊕)	Mass (M⊕)	Period (d)	Eq. T (K)	Year
GJ 876 d	Sub-Neptune	2.51	6.83	1.938	—	2005
GJ 876 c	Gas Giant	14.00	226.98	30.088	—	2000
GJ 876 b	Gas Giant	13.30	723.22	61.117	—	1998
GJ 876 e this	Sub-Neptune	3.92	14.60	124.260	—	2010

GJ 876 e Planet Profile

Physical Specs

Radius

3.92 R⊕

Radius (Jupiter)

0.350 R♃

Mass

14.60 M⊕

Mass (Jupiter)

0.046 M♃

Density

1.33 g/cm³

Surface Gravity

0.95 g (Earth)

Classification

Planet Type

Sub-Neptune

ESI Score 0.550

HZ Position Unknown

Controversial No

Discovery

Year 2010

Method Radial Velocity

Facility W. M. Keck Observatory

Telescope 10 m Keck I Telescope

Size rank in cohort

Rank by radius

#17of 1978

top 0.8%

This planet

3.92R⊕

Sub-Neptune median

2.71R⊕

Nearest-size peers

OGLE-2017-BLG-1691L b 3.92 R⊕ Kepler-1810 b 3.92 R⊕ Kepler-1024 b 3.91 R⊕

Metric	Earth	GJ 876 e	Jupiter
Radius (R⊕)	1.00	3.92	11.21
Mass (M⊕)	1.00	14.60	317.83
Density (g/cm³)	5.51	1.33	1.33
Surface Gravity (g)	1.00	0.95	2.53
Insolation (S⊕)	1.00	—	0.037

Alternative Mass Estimates

Method	Value	Interpretation
Best measured mass	14.600 M⊕	Direct mass measurement (not derived).
Minimum mass (M sin i)	15.430 M⊕	Lower bound from radial-velocity fitting.
Computed mass	18.001 M⊕	Model-computed mass (e.g. from mass-radius relation).

Star Catalogue Identifiers

HIP

HIP 113020

TIC

TIC 188580272

Gaia DR2

Gaia DR2 2603090003484152064

Gaia DR3

Gaia DR3 2603090003484152064

System

GJ 876

Percentile among Sub-Neptune cohort

Radius 3.920 R⊕ · percentile 99 / cohort 1978

Mass 14.600 M⊕ · percentile 92 / cohort 1978

Orbital period 124.26 d · percentile 95 / cohort 1946

Distance 4.68 pc · percentile 0 / cohort 1975

ESI 0.550 · percentile 76 / cohort 1978

Orbit & Habitability

Orbital Dynamics

Period

124.260 days

Semi-major axis

0.3343 AU

Eccentricity

0.055

Inclination

59.00 °

Year Length

A year here lasts approximately 124.26 Earth days (34.0% of a terrestrial year) on a nearly circular orbit at a mean orbital distance of 0.3343 AU.

Eq. Temperature

—

Insolation (S⊕)

—

Earth = 1.00

Earth Similarity (ESI)

0.550

0 = alien, 1 = Earth-identical

Discovery Paper

Primary reference

Rivera et al. 2010

Instrument

HIRES Spectrometer

Publication

2010-08

Observation locale

Ground

Discovery cohort

Planets confirmed in 2010 at W. M. Keck Observatory (12 shown).

HD 156668 b · Super-Earth HD 1461 b · Sub-Neptune HAT-P-17 c · Gas Giant HD 97658 b · Sub-Neptune HD 163607 c · Gas Giant HD 177830 c · Neptune-like HD 218566 b · Neptune-like HD 102956 b · Gas Giant HD 163607 b · Gas Giant GJ 1148 b · Gas Giant HD 31253 b · Gas Giant HD 164509 b · Gas Giant

Host System: GJ 876

Spectral Class

M-type red dwarf

Effective Temperature

3,294 K — cooler than the Sun (5,778 K)

Estimated Age

1.00 Gyr — younger than the Sun (4.6 Gyr)

Stellar Radius

0.300 R☉

Stellar Mass

0.320 M☉

Metallicity [Fe/H]

0.21

Extended Stellar Properties

Surface gravity (log g)

4.872 dex

Stellar density

10.866 g/cm³

Systemic radial velocity

-1.60 km/s

Rotational v·sin i

0.16 km/s

Metallicity ratio

[Fe/H]

Distance

4.68 parsec

Light-years 15.25 ly

V-band magnitude

10.16 mag

Voyager-speed travel 268,905 yr

Multi-band Host Photometry — 13 bands

Astrometric Data

Parallax

213.867 mas

Total Proper Motion

1,171.101 mas/yr

PM Right Ascension

957.96 mas/yr

PM Declination

-673.64 mas/yr

Galactic Cartesian (pc)

x = 0.928 · y = -0.278 · z = -0.246

Equatorial (J2000)

RA 343.32397° · Dec -14.26660°

Galactic ℓ, b

52.003° · -59.635°

Ecliptic λ, β

339.168° · -6.631°

HTM-20 index

-1428809485

Observation Record

Photometric series

RV measurements

Stellar spectra