GJ 180 b
Astrophysical Synthesis & Habitability Characterization
GJ 180 b is a confirmed sub-neptune exoplanet orbiting the star GJ 180, located approximately 38.9 light-years (11.94 parsecs) from the Solar System. First announced in 2014 by Multiple Observatories using the Radial Velocity detection technique (measuring periodic Doppler reflex motion in the host star's spectrum), this world measures 2.43 Earth radii and has a measured mass of 6.49 Earth masses. Combining its mass and radius yields a mean bulk density of 2.49 g/cm³ (an intermediate density indicative of a deep water-ice mantle or dense volatile envelope), a surface gravity of 1.1 g⊕ (10.79 m/s²), and an escape velocity of 18.3 km/s.
In its orbital architecture around GJ 180, GJ 180 b completes one full revolution every 17.133 Earth days at a semi-major axis of 0.092 AU (orbiting interior to Mercury's 0.387 AU benchmark in the Solar System). Its mean orbital velocity is approximately 58.4 km/s (compared to Earth's 29.8 km/s). Its moderate orbital eccentricity of e = 0.07 carries the world between 0.0856 AU at periapsis and 0.0984 AU at apoapsis, driving measurable seasonal insolation cycles.
☁️ Atmospheric Regime (Volatile / Gas Envelope): With a radius of 2.430 R⊕, GJ 180 b exceeds the empirical ~1.8–2.2 R⊕ Fulton radius valley threshold, indicating a substantial hydrogen-helium or supercritical volatile envelope without a conventional solid terrestrial surface.
The host star GJ 180 is classified as a low-mass red dwarf of spectral type M3 with an effective photospheric temperature of 3,371 K, a radius of 0.413 R☉, a mass of 0.43 M☉, an estimated bolometric luminosity of 0.02 L☉. From Earth, GJ 180 shines at apparent V-band magnitude 10.914 (faint and requiring research-grade or CCD telescopic photometry) in the Southern celestial hemisphere. The GJ 180 system is a multi-planet architecture hosting 3 confirmed worlds, with GJ 180 b sharing its stellar neighborhood alongside GJ 180 c, GJ 180 d.
Methodology: Computed using the Schulze-Makuch et al. (2011) weighted metric comparing physical interior (radius, estimated density) and surface thermal regime (escape velocity, equilibrium temperature).
Discovery Facility: Multiple Observatories · Catalogue Source: NASA Exoplanet Archive (IPAC / Caltech).
☀️ Host Star Telemetry
| Host Star Name | GJ 180 |
| Spectral Type | M3 |
| Effective Temp (Teff) | 3,371 K |
| Stellar Radius | 0.4130 R☉ |
| Stellar Mass | 0.4300 M☉ |
| Bolometric Luminosity | 0.02 L☉ |
| Metallicity [Fe/H] | — |
| Stellar Age | — |
| Apparent Magnitude | V: 10.914 · G: 9.934 |
| System Architecture | 1 Star, 3 Planets |
🪐 Orbital & Physical Dynamics
| Semi-Major Axis (a) | 0.092000 AU |
| Orbital Period | 17.133 days |
| Mean Orbital Velocity | 58.4 km/s |
| Orbital Eccentricity (e) | 0.07000 |
| Orbital Inclination (i) | — |
| Mean Bulk Density | 2.49 g/cm³ (18.3 km/s vesc) |
| Insolation Flux | 1.5359 S⊕ (~2,090 W/m²) |
| Habitable Zone Status | Exterior / Non-HZ |
| Celestial Distance | 38.900 LY (11.941 pc) |