Kepler-473 b
Astrophysical Synthesis & Habitability Characterization
Kepler-473 b is a confirmed sub-neptune exoplanet orbiting the star Kepler-473, located approximately 2954.8 light-years (905.94 parsecs) from the Solar System. First announced in 2016 by Kepler using the Transit detection technique (producing an estimated primary transit depth of 0.0779% across the stellar disk), this world measures 4.08 Earth radii (0.36 Jupiter radii) and has a measured mass of 15.6 Earth masses. Combining its mass and radius yields a mean bulk density of 1.27 g/cm³ (a low bulk density dominated by an extended hydrogen-helium gaseous envelope), a surface gravity of 0.94 g⊕ (9.22 m/s²), and an escape velocity of 21.9 km/s.
In its orbital architecture around Kepler-473, Kepler-473 b completes one full revolution every 14.557 Earth days at a semi-major axis of 0.12048 AU (orbiting interior to Mercury's 0.387 AU benchmark in the Solar System). Its mean orbital velocity is approximately 90 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 879 K (+606°C / +1123°F) and receiving 243.38 S⊕ (~331,235 W/m²), Kepler-473 b orbits interior to the runaway greenhouse boundary where surface liquid water cannot persist.
The host star Kepler-473 is classified as a stellar host with an effective photospheric temperature of 5,816 K, a radius of 1.34 R☉, a mass of 1.06 M☉, an estimated bolometric luminosity of 1.843 L☉. Stellar evolution modeling indicates an estimated stellar age of 6.92 Gyr and a metallicity of [Fe/H] = 0.12 dex (metal-rich relative to the Sun). From Earth, Kepler-473 shines at apparent V-band magnitude 13.548 (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: Kepler · Catalogue Source: NASA Exoplanet Archive (IPAC / Caltech).
☀️ Host Star Telemetry
| Host Star Name | Kepler-473 |
| Spectral Type | Unclassified |
| Effective Temp (Teff) | 5,816 K |
| Stellar Radius | 1.3400 R☉ |
| Stellar Mass | 1.0600 M☉ |
| Bolometric Luminosity | 1.843 L☉ |
| Metallicity [Fe/H] | 0.120 dex |
| Stellar Age | 6.920 Gyr |
| Apparent Magnitude | V: 13.548 · G: 13.369 |
| System Architecture | 1 Star, 1 Planet |
🪐 Orbital & Physical Dynamics
| Semi-Major Axis (a) | 0.120480 AU |
| Orbital Period | 14.557 days |
| Mean Orbital Velocity | 90 km/s |
| Orbital Eccentricity (e) | 0.00000 |
| Orbital Inclination (i) | 89.8600° |
| Mean Bulk Density | 1.27 g/cm³ (21.9 km/s vesc) |
| Insolation Flux | 243.3760 S⊕ (~331,235 W/m²) |
| Habitable Zone Status | Exterior / Non-HZ |
| Celestial Distance | 2954.800 LY (905.937 pc) |