Super-Earth · GJ 251

GJ 251 b

ExoplanetsDiscovered 2020

Scientific overview

GJ 251 b is a super-earth orbiting GJ 251, completing an orbit every 14 days, about 18 light-years from Earth. It was discovered in 2020 using the radial velocity method.

Host star

GJ 251

Spectral type

M3.0 V

Temperature

3,342 K

Mass

0.35 M☉

Planetary system — GJ 251 system

View the GJ 251 system (2 known planets).

Planet	Class	Radius (R⊕)	Period (d)	Distance (ly)
GJ 251 bRadial Velocity · 2020	Super-Earth	1.79	14.237	18
GJ 251 cRadial Velocity · 2025	Super-Earth	1.8	53.647	18

Discovery and detection

Detection method

Radial Velocity Method

Discovery year

2020

Discovered at

W. M. Keck Observatory

Knowledge connections

OrbitsGJ 251
Member of systemGJ 251 system
Discovered by methodRadial Velocity Method
Discovered atW. M. Keck Observatory
Catalogued inNASA Exoplanet Archive

Quick facts

Class: Super-Earth
Host star: GJ 251
Discovery method: Radial Velocity Method
Discovery year: 2020
Orbital period: 14.237 d
Semi-major axis: 0.0808 AU
Eccentricity: 0
Radius: 1.79 R⊕
Mass: 3.85 M⊕
Density: 3.70 g/cm³ · derived
Equilibrium temp.: 336 K
Insolation: 2.37 S⊕
Distance: 18 ly

Density is derived from the archive mass and radius via ρ = M / (4⁄3·π·r³); all other values are catalogued measurements.

Derived values

Computed from source-backed inputs via standard formulae — not observations. Every input and constant is traced below.

Bulk density3.70 g/cm³derived
Formula & inputs
Formula: ρ = M / (4⁄3·π·r³) (v1.0.0, impl v1.0.0)
Inputs:
- massEarth = 3.85 M⊕ · NASA
- radiusEarth = 1.79 R⊕ · NASA
Assumptions: M⊕ = 5.972e+24 kg, R⊕ = 6371000 m (IAU 2015 B3 nominal); Assumes a uniform sphere.
Limitations: Withheld above 30 g/cm³ (inconsistent mass/radius inputs).; Archive mass/radius carry no propagated uncertainty here.
Uncertainty: not propagated (inputs carry no catalogued uncertainty)
Computed as of 2026-06-29.

Quality & authority

Partial

Unreviewed

Description: Complete
Source coverage: Partial
Relationship coverage: Complete
Review coverage: None
Citation coverage: None
Image coverage: Not applicable

Data from the NASA Exoplanet Archive. See source quality.