Key parameters at a glance

A radius of 2.34 Earth radii
A mass of 6.10 Earth masses
Surface gravity around 1.11 g
An orbital period of 50.770 days
Semi-major axis 0.2120 AU
Equilibrium temperature 241 K (-32 °C)
Distance from Earth 10.72 light-years
Earth Similarity Index 0.693
Travel time at Voyager 1 speed 189,048 years

3 siblings around GJ 887

GJ 887 d 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 887 e	Rocky Terrestrial	1.12	1.46	4.425	544	2026
GJ 887 b	Super-Earth	1.80	3.90	9.262	426	2020
GJ 887 c	Sub-Neptune	2.43	6.50	21.784	320	2020
GJ 887 d this	Sub-Neptune	2.34	6.10	50.770	241	2026

GJ 887 d Planet Profile

Physical Specs

Radius

2.34 R⊕

Radius (Jupiter)

0.209 R♃

Mass

6.10 M⊕

Mass (Jupiter)

0.019 M♃

Density

2.62 g/cm³

Surface Gravity

1.11 g (Earth)

Classification

Planet Type

Sub-Neptune

ESI Score 0.693

HZ Position Habitable

Controversial No

Discovery

Year 2026

Method Radial Velocity

Facility Multiple Observatories

Telescope Multiple Telescopes

Size rank in cohort

Rank by radius

#1429of 1978

top 72.2%

This planet

2.34R⊕

Sub-Neptune median

2.71R⊕

Nearest-size peers

Kepler-246 b 2.34 R⊕ Kepler-275 b 2.34 R⊕ Kepler-338 c 2.34 R⊕

Metric	Earth	GJ 887 d	Jupiter
Radius (R⊕)	1.00	2.34	11.21
Mass (M⊕)	1.00	6.10	317.83
Density (g/cm³)	5.51	2.62	1.33
Surface Gravity (g)	1.00	1.11	2.53
Insolation (S⊕)	1.00	0.81	0.037

Alternative Mass Estimates

Method	Value	Interpretation
Minimum mass (M sin i)	6.100 M⊕	Lower bound from radial-velocity fitting.

Star Catalogue Identifiers

HD 217987

HIP

HIP 114046

TIC

TIC 155315739

Gaia DR2

Gaia DR2 6553614253923452800

Gaia DR3

Gaia DR3 6553614253923452800

System

GJ 887

Percentile among Sub-Neptune cohort

Radius 2.340 R⊕ · percentile 27 / cohort 1978

Mass 6.100 M⊕ · percentile 27 / cohort 1978

Orbital period 50.77 d · percentile 85 / cohort 1946

Distance 3.29 pc · percentile 0 / cohort 1975

ESI 0.693 · percentile 92 / cohort 1978

Orbit & Habitability

Orbital Dynamics

Period

50.770 days

Semi-major axis

0.2120 AU

Eccentricity

—

Inclination

— °

Year Length

A year here lasts approximately 50.77 Earth days (13.9% of a terrestrial year) at a mean orbital distance of 0.2120 AU.

Eq. Temperature

241K

(-32 °C)

Insolation (S⊕)

0.81

Earth = 1.00

Earth Similarity (ESI)

0.693

0 = alien, 1 = Earth-identical

Within the conservative habitable zone — surface water would be frozen.

Discovery Paper

Primary reference

Hartogh et al. 2026

Instrument

Multiple Instruments

Publication

2026-02

Observation locale

Ground

Discovery cohort

Planets confirmed in 2026 at Multiple Observatories (12 shown).

DMPP-6 b · Sub-Neptune TOI-4336 A c · Super-Earth HD 176986 d · Sub-Neptune GJ 887 e · Rocky Terrestrial DMPP-6 c · Sub-Neptune DMPP-9 b · Sub-Neptune TOI-5789 d · Super-Earth TOI-5789 e · Sub-Neptune HD 85426 c · Sub-Neptune DMPP-2 c · Neptune-like DMPP-7 b · Neptune-like TOI-375 d · Gas Giant

Host System: GJ 887

Spectral Class

M-type red dwarf

Effective Temperature

3,688 K — cooler than the Sun (5,778 K)

Estimated Age

2.90 Gyr — younger than the Sun (4.6 Gyr)

Stellar Radius

0.468 R☉

Stellar Mass

0.495 M☉

Metallicity [Fe/H]

-0.06

Extended Stellar Properties

Surface gravity (log g)

4.156 dex

Stellar density

6.056 g/cm³

Systemic radial velocity

8.17 km/s

Rotational v·sin i

2.50 km/s

Rotation period

38.70 days

Metallicity ratio

[Fe/H]

Distance

3.29 parsec

Light-years 10.72 ly

V-band magnitude

7.56 mag

Voyager-speed travel 189,048 yr

Multi-band Host Photometry — 8 bands

Astrometric Data

Parallax

304.219 mas

Total Proper Motion

6,895.546 mas/yr

PM Right Ascension

6,765.99 mas/yr

PM Declination

1,330.39 mas/yr

Galactic Cartesian (pc)

x = 0.788 · y = -0.189 · z = -0.586

Equatorial (J2000)

RA 346.50276° · Dec -35.84735°

Galactic ℓ, b

5.097° · -65.987°

Ecliptic λ, β

332.713° · -27.519°

HTM-20 index

215838338