Kepler-331 b
Astrophysical Synthesis & Habitability Characterization
Kepler-331 b is a confirmed super-earth exoplanet orbiting the star Kepler-331, located approximately 1892.1 light-years (580.12 parsecs) from the Solar System. First announced in 2014 by Kepler using the Transit detection technique (producing an estimated primary transit depth of 0.115% across the stellar disk), this world measures 1.82 Earth radii and has a measured mass of 3.97 Earth masses. Combining its mass and radius yields a mean bulk density of 3.63 g/cm³ (an intermediate density indicative of a deep water-ice mantle or dense volatile envelope), a surface gravity of 1.2 g⊕ (11.77 m/s²), and an escape velocity of 16.5 km/s.
In its orbital architecture around Kepler-331, Kepler-331 b completes one full revolution every 8.457 Earth days at a semi-major axis of 0.065 AU (orbiting interior to Mercury's 0.387 AU benchmark in the Solar System). Its mean orbital velocity is approximately 83.6 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 540 K (+267°C / +513°F) and receiving 35.98 S⊕ (~48,974 W/m²), Kepler-331 b orbits interior to the runaway greenhouse boundary where surface liquid water cannot persist.
The host star Kepler-331 is classified as a stellar host with an effective photospheric temperature of 4,347 K, a radius of 0.492 R☉, a mass of 0.653 M☉, an estimated bolometric luminosity of 0.078 L☉. Stellar evolution modeling indicates an estimated stellar age of 1.2 Gyr and a metallicity of [Fe/H] = 0.118 dex (metal-rich relative to the Sun). From Earth, Kepler-331 shines at apparent V-band magnitude 16.199 (faint and requiring research-grade or CCD telescopic photometry) in the Northern celestial hemisphere. The Kepler-331 system is a multi-planet architecture hosting 3 confirmed worlds, with Kepler-331 b sharing its stellar neighborhood alongside Kepler-331 c, Kepler-331 d.
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-331 |
| Spectral Type | Unclassified |
| Effective Temp (Teff) | 4,347 K |
| Stellar Radius | 0.4920 R☉ |
| Stellar Mass | 0.6530 M☉ |
| Bolometric Luminosity | 0.078 L☉ |
| Metallicity [Fe/H] | 0.118 dex |
| Stellar Age | 1.200 Gyr |
| Apparent Magnitude | V: 16.199 · G: 15.836 |
| System Architecture | 1 Star, 3 Planets |
🪐 Orbital & Physical Dynamics
| Semi-Major Axis (a) | 0.065000 AU |
| Orbital Period | 8.457 days |
| Mean Orbital Velocity | 83.6 km/s |
| Orbital Eccentricity (e) | 0.00000 |
| Orbital Inclination (i) | 89.5800° |
| Mean Bulk Density | 3.63 g/cm³ (16.5 km/s vesc) |
| Insolation Flux | 35.9840 S⊕ (~48,974 W/m²) |
| Habitable Zone Status | Exterior / Non-HZ |
| Celestial Distance | 1892.100 LY (580.119 pc) |