GJ 480 b
Astrophysical Synthesis & Habitability Characterization
GJ 480 b is a confirmed sub-neptune exoplanet orbiting the star GJ 480, located approximately 46.4 light-years (14.24 parsecs) from the Solar System. First announced in 2020 by Multiple Observatories using the Radial Velocity detection technique (measuring periodic Doppler reflex motion in the host star's spectrum), this world measures 2.91 Earth radii and has a measured mass of 8.8 Earth masses. Combining its mass and radius yields a mean bulk density of 1.97 g/cm³ (a low bulk density dominated by an extended hydrogen-helium gaseous envelope), a surface gravity of 1.04 g⊕ (10.2 m/s²), and an escape velocity of 19.5 km/s.
In its orbital architecture around GJ 480, GJ 480 b completes one full revolution every 9.554 Earth days at a semi-major axis of 0.068 AU (orbiting interior to Mercury's 0.387 AU benchmark in the Solar System). Its mean orbital velocity is approximately 77.4 km/s (compared to Earth's 29.8 km/s). The orbit is modeled as circular (e = 0.00), maintaining a constant stellar distance throughout its year.
⚠️ Thermal Regime (Irradiated / Hot Zone): At an equilibrium temperature of 406 K (+133°C / +271°F) and receiving 5.93 S⊕ (~8,069 W/m²), GJ 480 b orbits interior to the runaway greenhouse boundary where surface liquid water cannot persist.
The host star GJ 480 is classified as a low-mass red dwarf of spectral type M3.5 Ve with an effective photospheric temperature of 3,509 K, a radius of 0.449 R☉, a mass of 0.45 M☉, an estimated bolometric luminosity of 0.027 L☉. Stellar evolution modeling indicates a metallicity of [Fe/H] = 0.26 dex (metal-rich relative to the Sun). From Earth, GJ 480 shines at apparent V-band magnitude 11.49 (faint and requiring research-grade or CCD telescopic photometry) in the Northern celestial hemisphere.
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 480 |
| Spectral Type | M3.5 Ve |
| Effective Temp (Teff) | 3,509 K |
| Stellar Radius | 0.4490 R☉ |
| Stellar Mass | 0.4500 M☉ |
| Bolometric Luminosity | 0.027 L☉ |
| Metallicity [Fe/H] | 0.260 dex |
| Stellar Age | — |
| Apparent Magnitude | V: 11.490 · G: 10.325 |
| System Architecture | 1 Star, 1 Planet |
🪐 Orbital & Physical Dynamics
| Semi-Major Axis (a) | 0.068000 AU |
| Orbital Period | 9.554 days |
| Mean Orbital Velocity | 77.4 km/s |
| Orbital Eccentricity (e) | 0.00000 |
| Orbital Inclination (i) | — |
| Mean Bulk Density | 1.97 g/cm³ (19.5 km/s vesc) |
| Insolation Flux | 5.9290 S⊕ (~8,069 W/m²) |
| Habitable Zone Status | Exterior / Non-HZ |
| Celestial Distance | 46.400 LY (14.236 pc) |