GJ 433 b
Astrophysical Synthesis & Habitability Characterization
GJ 433 b is a confirmed sub-neptune exoplanet orbiting the star GJ 433, located approximately 29.6 light-years (9.07 parsecs) from the Solar System. First announced in 2013 by La Silla Observatory using the Radial Velocity detection technique (measuring periodic Doppler reflex motion in the host star's spectrum), this world measures 2.33 Earth radii and has a measured mass of 6.043 Earth masses. Combining its mass and radius yields a mean bulk density of 2.63 g/cm³ (an intermediate density indicative of a deep water-ice mantle or dense volatile envelope), a surface gravity of 1.11 g⊕ (10.89 m/s²), and an escape velocity of 18 km/s.
In its orbital architecture around GJ 433, GJ 433 b completes one full revolution every 7.371 Earth days at a semi-major axis of 0.062 AU (orbiting interior to Mercury's 0.387 AU benchmark in the Solar System). Its mean orbital velocity is approximately 91.5 km/s (compared to Earth's 29.8 km/s). With a near-circular eccentricity of e = 0.04 (ranging from 0.0595 AU at periapsis to 0.0645 AU at apoapsis), the planet experiences minimal orbital distance variation.
⚠️ Thermal Regime (Irradiated / Hot Zone): At an equilibrium temperature of 474 K (+201°C / +394°F) and receiving 5.20 S⊕ (~7,081 W/m²), GJ 433 b orbits interior to the runaway greenhouse boundary where surface liquid water cannot persist.
The host star GJ 433 is classified as a low-mass red dwarf of spectral type M2V with an effective photospheric temperature of 3,461 K, a radius of 0.5 R☉, a mass of 0.48 M☉, an estimated bolometric luminosity of 0.032 L☉. Stellar evolution modeling indicates a metallicity of [Fe/H] = -0.17 dex (metal-poor relative to the Sun). From Earth, GJ 433 shines at apparent V-band magnitude 9.81 (accessible to binoculars and small amateur telescopes) in the Southern celestial hemisphere. The GJ 433 system is a multi-planet architecture hosting 3 confirmed worlds, with GJ 433 b sharing its stellar neighborhood alongside GJ 433 d, GJ 433 c.
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: La Silla Observatory · Catalogue Source: NASA Exoplanet Archive (IPAC / Caltech).
☀️ Host Star Telemetry
| Host Star Name | GJ 433 |
| Spectral Type | M2V |
| Effective Temp (Teff) | 3,461 K |
| Stellar Radius | 0.5000 R☉ |
| Stellar Mass | 0.4800 M☉ |
| Bolometric Luminosity | 0.032 L☉ |
| Metallicity [Fe/H] | -0.170 dex |
| Stellar Age | — |
| Apparent Magnitude | V: 9.810 · G: 8.891 |
| System Architecture | 1 Star, 3 Planets |
🪐 Orbital & Physical Dynamics
| Semi-Major Axis (a) | 0.062000 AU |
| Orbital Period | 7.371 days |
| Mean Orbital Velocity | 91.5 km/s |
| Orbital Eccentricity (e) | 0.04000 |
| Orbital Inclination (i) | — |
| Mean Bulk Density | 2.63 g/cm³ (18 km/s vesc) |
| Insolation Flux | 5.2029 S⊕ (~7,081 W/m²) |
| Habitable Zone Status | Exterior / Non-HZ |
| Celestial Distance | 29.600 LY (9.065 pc) |