GJ 3634 b
Astrophysical Synthesis & Habitability Characterization
GJ 3634 b is a confirmed sub-neptune exoplanet orbiting the star GJ 3634, located approximately 66.5 light-years (20.38 parsecs) from the Solar System. First announced in 2010 by La Silla Observatory using the Radial Velocity detection technique (measuring periodic Doppler reflex motion in the host star's spectrum), this world measures 2.83 Earth radii and has a measured mass of 8.4 Earth masses. Combining its mass and radius yields a mean bulk density of 2.04 g/cm³ (an intermediate density indicative of a deep water-ice mantle or dense volatile envelope), a surface gravity of 1.05 g⊕ (10.3 m/s²), and an escape velocity of 19.3 km/s.
In its orbital architecture around GJ 3634, GJ 3634 b completes one full revolution every 2.646 Earth days at a semi-major axis of 0.0287 AU (an ultra-close orbit less than one-seventh of Mercury's 0.387 AU distance from the Sun, where strong stellar tidal forces typically induce synchronous rotation). Its mean orbital velocity is approximately 118 km/s (compared to Earth's 29.8 km/s). Its moderate orbital eccentricity of e = 0.08 carries the world between 0.0264 AU at periapsis and 0.031 AU at apoapsis, driving measurable seasonal insolation cycles.
⚠️ Thermal Regime (Irradiated / Hot Zone): At an equilibrium temperature of 656 K (+383°C / +721°F) and receiving 24.28 S⊕ (~33,044 W/m²), GJ 3634 b orbits interior to the runaway greenhouse boundary where surface liquid water cannot persist.
The host star GJ 3634 is classified as a low-mass red dwarf of spectral type M2.5 with an effective photospheric temperature of 3,517 K, a radius of 0.43 R☉, a mass of 0.45 M☉, an estimated bolometric luminosity of 0.025 L☉. Stellar evolution modeling indicates an estimated stellar age of 5 Gyr. From Earth, GJ 3634 shines at apparent V-band magnitude 11.938 (faint and requiring research-grade or CCD telescopic photometry) in the Southern 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: La Silla Observatory · Catalogue Source: NASA Exoplanet Archive (IPAC / Caltech).
☀️ Host Star Telemetry
| Host Star Name | GJ 3634 |
| Spectral Type | M2.5 |
| Effective Temp (Teff) | 3,517 K |
| Stellar Radius | 0.4300 R☉ |
| Stellar Mass | 0.4500 M☉ |
| Bolometric Luminosity | 0.025 L☉ |
| Metallicity [Fe/H] | — |
| Stellar Age | 5.000 Gyr |
| Apparent Magnitude | V: 11.938 · G: 10.923 |
| System Architecture | 1 Star, 1 Planet |
🪐 Orbital & Physical Dynamics
| Semi-Major Axis (a) | 0.028700 AU |
| Orbital Period | 2.646 days |
| Mean Orbital Velocity | 118 km/s |
| Orbital Eccentricity (e) | 0.08000 |
| Orbital Inclination (i) | 59.0000° |
| Mean Bulk Density | 2.04 g/cm³ (19.3 km/s vesc) |
| Insolation Flux | 24.2793 S⊕ (~33,044 W/m²) |
| Habitable Zone Status | Exterior / Non-HZ |
| Celestial Distance | 66.500 LY (20.378 pc) |