GJ 3470 b
Astrophysical Synthesis & Habitability Characterization
GJ 3470 b is a confirmed sub-neptune exoplanet orbiting the star GJ 3470, located approximately 96 light-years (29.42 parsecs) from the Solar System. First announced in 2012 by La Silla Observatory using the Radial Velocity detection technique (measuring periodic Doppler reflex motion in the host star's spectrum), this world measures 4.57 Earth radii (0.41 Jupiter radii) and has a measured mass of 13.9 Earth masses. Combining its mass and radius yields a mean bulk density of 0.8 g/cm³ (a low bulk density dominated by an extended hydrogen-helium gaseous envelope), a surface gravity of 0.67 g⊕ (6.57 m/s²), and an escape velocity of 19.5 km/s.
In its orbital architecture around GJ 3470, GJ 3470 b completes one full revolution every 3.337 Earth days at a semi-major axis of 0.0355 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 115.7 km/s (compared to Earth's 29.8 km/s). With a near-circular eccentricity of e = 0.017 (ranging from 0.0349 AU at periapsis to 0.0361 AU at apoapsis), the planet experiences minimal orbital distance variation.
⚠️ Thermal Regime (Irradiated / Hot Zone): At an equilibrium temperature of 594 K (+321°C / +610°F) and receiving 29.66 S⊕ (~40,365 W/m²), GJ 3470 b orbits interior to the runaway greenhouse boundary where surface liquid water cannot persist.
The host star GJ 3470 is classified as a low-mass red dwarf of spectral type M1.5 with an effective photospheric temperature of 3,600 K, a radius of 0.547 R☉, a mass of 0.539 M☉, an estimated bolometric luminosity of 0.045 L☉. Stellar evolution modeling indicates an estimated stellar age of 1.65 Gyr and a metallicity of [Fe/H] = 0.2 dex (metal-rich relative to the Sun). From Earth, GJ 3470 shines at apparent V-band magnitude 12.332 (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: La Silla Observatory · Catalogue Source: NASA Exoplanet Archive (IPAC / Caltech).
☀️ Host Star Telemetry
| Host Star Name | GJ 3470 |
| Spectral Type | M1.5 |
| Effective Temp (Teff) | 3,600 K |
| Stellar Radius | 0.5470 R☉ |
| Stellar Mass | 0.5390 M☉ |
| Bolometric Luminosity | 0.045 L☉ |
| Metallicity [Fe/H] | 0.200 dex |
| Stellar Age | 1.650 Gyr |
| Apparent Magnitude | V: 12.332 · G: 11.354 |
| System Architecture | 1 Star, 1 Planet |
🪐 Orbital & Physical Dynamics
| Semi-Major Axis (a) | 0.035500 AU |
| Orbital Period | 3.337 days |
| Mean Orbital Velocity | 115.7 km/s |
| Orbital Eccentricity (e) | 0.01700 |
| Orbital Inclination (i) | 89.1300° |
| Mean Bulk Density | 0.8 g/cm³ (19.5 km/s vesc) |
| Insolation Flux | 29.6584 S⊕ (~40,365 W/m²) |
| Habitable Zone Status | Exterior / Non-HZ |
| Celestial Distance | 96.000 LY (29.421 pc) |