Key parameters at a glance

A radius of 1.80 Earth radii
A mass of 3.90 Earth masses
Surface gravity around 1.20 g
An orbital period of 9.262 days
Semi-major axis 0.0683 AU
Equilibrium temperature 426 K (153 °C)
Distance from Earth 10.72 light-years
Earth Similarity Index 0.641
Travel time at Voyager 1 speed 189,048 years
Almost certainly tidally locked to its host star given the close orbit

3 siblings around GJ 887

GJ 887 b 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 this	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	Sub-Neptune	2.34	6.10	50.770	241	2026

GJ 887 b Planet Profile

Physical Specs

Radius

1.80 R⊕

Radius (Jupiter)

0.161 R♃

Mass

3.90 M⊕

Mass (Jupiter)

0.012 M♃

Density

3.67 g/cm³

Surface Gravity

1.20 g (Earth)

Classification

Planet Type

Super-Earth

ESI Score 0.641

HZ Position Inner

Controversial No

Discovery

Year 2020

Method Radial Velocity

Facility La Silla Observatory

Telescope 3.6 m ESO Telescope

Size rank in cohort

Rank by radius

#253of 1176

top 21.4%

This planet

1.80R⊕

Super-Earth median

1.60R⊕

Nearest-size peers

PSR B1257+12 d 1.80 R⊕ Kepler-11 b 1.80 R⊕ Kepler-148 b 1.80 R⊕

Metric	Earth	GJ 887 b	Jupiter
Radius (R⊕)	1.00	1.80	11.21
Mass (M⊕)	1.00	3.90	317.83
Density (g/cm³)	5.51	3.67	1.33
Surface Gravity (g)	1.00	1.20	2.53
Insolation (S⊕)	1.00	7.80	0.037

Alternative Mass Estimates

Method	Value	Interpretation
Minimum mass (M sin i)	3.900 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 Super-Earth cohort

Radius 1.800 R⊕ · percentile 77 / cohort 1176

Mass 3.900 M⊕ · percentile 71 / cohort 1176

Orbital period 9.26 d · percentile 63 / cohort 1164

Distance 3.29 pc · percentile 0 / cohort 1171

ESI 0.641 · percentile 82 / cohort 1176

Orbit & Habitability

Orbital Dynamics

Period

9.262 days

Semi-major axis

0.0683 AU

Eccentricity

0.140

Inclination

— °

Year Length

A year here lasts approximately 9.26 Earth days (2.5% of a terrestrial year) on a mildly elliptical path at a mean orbital distance of 0.0683 AU.

Extended Orbital Architecture

RV semi-amplitude (K)

2.000 m/s

Transit mid-time (BJD)

2,453,492.7500

Long. of periastron (ω)

180.00°

Angular separation (arcsec)

20.80000

Eq. Temperature

426K

(153 °C)

Insolation (S⊕)

7.80

Earth = 1.00

Earth Similarity (ESI)

0.641

0 = alien, 1 = Earth-identical

Inside the inner HZ boundary (too hot for liquid water) — the surface is too hot to retain surface water. Close-orbiting tidally-locked around a cool host.

Discovery Paper

Primary reference

Jeffers et al. 2020

Instrument

HARPS Spectrograph

Publication

2020-06

Observation locale

Ground

Discovery cohort

Planets confirmed in 2020 at La Silla Observatory (4 shown).

GJ 1061 b · Rocky Terrestrial GJ 1061 d · Rocky Terrestrial GJ 1061 c · Rocky Terrestrial GJ 887 c · Sub-Neptune

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

Observation Record

Photometric series

Stellar spectra

Archive notes