GJ 3473 b
Astrophysical Synthesis & Habitability Characterization
GJ 3473 b is a confirmed super-earth exoplanet orbiting the star GJ 3473, located approximately 89.3 light-years (27.36 parsecs) from the Solar System. First announced in 2020 by Transiting Exoplanet Survey Satellite (TESS) using the Transit detection technique (producing an estimated primary transit depth of 0.1014% across the stellar disk), this world measures 1.264 Earth radii and has a measured mass of 1.86 Earth masses. Combining its mass and radius yields a mean bulk density of 5.08 g/cm³ (a terrestrial silicate-iron composition comparable to Earth (5.51 g/cm³)), a surface gravity of 1.16 g⊕ (11.38 m/s²), and an escape velocity of 13.6 km/s.
In its orbital architecture around GJ 3473, GJ 3473 b completes one full revolution every 1.198 Earth days at a semi-major axis of 0.01589 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 144.3 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 773 K (+500°C / +932°F) and receiving 59.40 S⊕ (~80,843 W/m²), GJ 3473 b orbits interior to the runaway greenhouse boundary where surface liquid water cannot persist.
The host star GJ 3473 is classified as a low-mass red dwarf of spectral type M4 with an effective photospheric temperature of 3,347 K, a radius of 0.364 R☉, a mass of 0.36 M☉, an estimated bolometric luminosity of 0.015 L☉. Stellar evolution modeling indicates a metallicity of [Fe/H] = 0.11 dex (metal-rich relative to the Sun). From Earth, GJ 3473 shines at apparent V-band magnitude 13.74 (faint and requiring research-grade or CCD telescopic photometry) in the Northern celestial hemisphere. The GJ 3473 system is a multi-planet architecture hosting 2 confirmed worlds, with GJ 3473 b sharing its stellar neighborhood alongside GJ 3473 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: Transiting Exoplanet Survey Satellite (TESS) · Catalogue Source: NASA Exoplanet Archive (IPAC / Caltech).
☀️ Host Star Telemetry
| Host Star Name | GJ 3473 |
| Spectral Type | M4 |
| Effective Temp (Teff) | 3,347 K |
| Stellar Radius | 0.3640 R☉ |
| Stellar Mass | 0.3600 M☉ |
| Bolometric Luminosity | 0.015 L☉ |
| Metallicity [Fe/H] | 0.110 dex |
| Stellar Age | — |
| Apparent Magnitude | V: 13.740 · G: 12.465 |
| System Architecture | 2 Stars, 2 Planets |
🪐 Orbital & Physical Dynamics
| Semi-Major Axis (a) | 0.015890 AU |
| Orbital Period | 1.198 days |
| Mean Orbital Velocity | 144.3 km/s |
| Orbital Eccentricity (e) | 0.00000 |
| Orbital Inclination (i) | 87.9500° |
| Mean Bulk Density | 5.08 g/cm³ (13.6 km/s vesc) |
| Insolation Flux | 59.4000 S⊕ (~80,843 W/m²) |
| Habitable Zone Status | Exterior / Non-HZ |
| Celestial Distance | 89.300 LY (27.364 pc) |