Key parameters at a glance
- A radius of 13.30 Earth radii
- A mass of 723.22 Earth masses
- Surface gravity around 4.09 g
- An orbital period of 61.117 days
- Semi-major axis 0.2083 AU
- Distance from Earth 15.25 light-years
- Earth Similarity Index 0.376
- Travel time at Voyager 1 speed 268,905 years
3 siblings around GJ 876
GJ 876 b shares its host star with 3 other confirmed planets. Side-by-side measurements below.
GJ 876 b Planet Profile
Physical Specs
Classification
Planet Type
Gas Giant
Discovery
Size rank in cohort
Rank by radius
#793of 1771
top 44.7%
This planet
13.30R⊕
Gas Giant median
13.52R⊕
Nearest-size peers
| Metric | Earth | GJ 876 b | Jupiter |
|---|---|---|---|
| Radius (R⊕) | 1.00 | 13.30 | 11.21 |
| Mass (M⊕) | 1.00 | 723.22 | 317.83 |
| Density (g/cm³) | 5.51 | 1.69 | 1.33 |
| Surface Gravity (g) | 1.00 | 4.09 | 2.53 |
| Insolation (S⊕) | 1.00 | — | 0.037 |
Alternative Mass Estimates
| Method | Value | Interpretation |
|---|---|---|
| Best measured mass | 723.224 M⊕ | Direct mass measurement (not derived). |
| Minimum mass (M sin i) | 760.900 M⊕ | Lower bound from radial-velocity fitting. |
| Computed mass | 887.691 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 Gas Giant cohort
Orbit & Habitability
Orbital Dynamics
Year Length
A year here lasts approximately 61.12 Earth days (16.7% of a terrestrial year) on a nearly circular orbit at a mean orbital distance of 0.2083 AU.
Extended Orbital Architecture
RV semi-amplitude (K)
214.000 m/s
Transit mid-time (BJD)
2,453,055.9840
Long. of periastron (ω)
50.30°
Angular separation (arcsec)
44.60000
Eq. Temperature
—
Insolation (S⊕)
—
Earth = 1.00
Earth Similarity (ESI)
0.376
0 = alien, 1 = Earth-identical
Detection Signatures
Radial velocity
Stellar wobble has been measured spectroscopically.
Astrometry
Positional wobble of the host star was measured.
Discovery Paper
Primary reference
Marcy et al. 1998Instrument
Multiple Instruments
Publication
1998-10
Observation locale
Ground
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]
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
3
RV measurements
4
Stellar spectra
13
Similar Worlds
GJ 317 b
Gas Giant · M-type red dwarf
Radius 13.30 R⊕ · 49.6 ly
GJ 896 A b
Gas Giant · M-type red dwarf
Radius 13.30 R⊕ · 20.4 ly
GJ 328 b
Gas Giant · M-type red dwarf
Radius 13.30 R⊕ · 66.9 ly
TIC 46432937 b
Gas Giant · M-type red dwarf
Radius 13.32 R⊕ · 295.3 ly
HIP 79431 b
Gas Giant · M-type red dwarf
Radius 13.40 R⊕ · 47.4 ly
HIP 12961 b
Gas Giant · M-type red dwarf
Radius 13.20 R⊕ · 76.2 ly