Kepler-396 b
Astrophysical Synthesis & Habitability Characterization
Kepler-396 b is a confirmed sub-neptune exoplanet orbiting the star Kepler-396, located approximately 729.8 light-years (223.76 parsecs) from the Solar System. First announced in 2013 by Kepler using the Transit detection technique (producing an estimated primary transit depth of 0.0916% across the stellar disk), this world measures 3.5 Earth radii (0.31 Jupiter radii) and has a measured mass of 75.5 Earth masses (0.24 Jupiter masses). Combining its mass and radius yields a mean bulk density of 9.71 g/cm³ (an iron-enriched, high-compression rocky core), a surface gravity of 6.16 g⊕ (60.41 m/s²), and an escape velocity of 52 km/s.
In its orbital architecture around Kepler-396, Kepler-396 b completes one full revolution every 42.994 Earth days at a semi-major axis of 0.24067 AU (orbiting interior to Mercury's 0.387 AU benchmark in the Solar System). Its mean orbital velocity is approximately 60.9 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 496 K (+223°C / +433°F) and receiving 13.73 S⊕ (~18,688 W/m²), Kepler-396 b orbits interior to the runaway greenhouse boundary where surface liquid water cannot persist.
The host star Kepler-396 is classified as a stellar host with an effective photospheric temperature of 5,656 K, a radius of 1.06 R☉, a mass of 0.85 M☉, an estimated bolometric luminosity of 1.032 L☉. Stellar evolution modeling indicates an estimated stellar age of 0.62 Gyr and a metallicity of [Fe/H] = 0.156 dex (metal-rich relative to the Sun). From Earth, Kepler-396 shines at apparent V-band magnitude 12.259 (faint and requiring research-grade or CCD telescopic photometry) in the Northern celestial hemisphere. The Kepler-396 system is a multi-planet architecture hosting 2 confirmed worlds, with Kepler-396 b sharing its stellar neighborhood alongside Kepler-396 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: Kepler · Catalogue Source: NASA Exoplanet Archive (IPAC / Caltech).
☀️ Host Star Telemetry
| Host Star Name | Kepler-396 |
| Spectral Type | Unclassified |
| Effective Temp (Teff) | 5,656 K |
| Stellar Radius | 1.0600 R☉ |
| Stellar Mass | 0.8500 M☉ |
| Bolometric Luminosity | 1.032 L☉ |
| Metallicity [Fe/H] | 0.156 dex |
| Stellar Age | 0.620 Gyr |
| Apparent Magnitude | V: 12.259 · G: 11.829 |
| System Architecture | 1 Star, 2 Planets |
🪐 Orbital & Physical Dynamics
| Semi-Major Axis (a) | 0.240670 AU |
| Orbital Period | 42.994 days |
| Mean Orbital Velocity | 60.9 km/s |
| Orbital Eccentricity (e) | 0.00000 |
| Orbital Inclination (i) | 89.3400° |
| Mean Bulk Density | 9.71 g/cm³ (52 km/s vesc) |
| Insolation Flux | 13.7310 S⊕ (~18,688 W/m²) |
| Habitable Zone Status | Exterior / Non-HZ |
| Celestial Distance | 729.800 LY (223.757 pc) |