Kepler-317 b
Astrophysical Synthesis & Habitability Characterization
Kepler-317 b is a confirmed sub-neptune exoplanet orbiting the star Kepler-317, located approximately 3067.8 light-years (940.58 parsecs) from the Solar System. First announced in 2014 by Kepler using the Transit detection technique (producing an estimated primary transit depth of 0.0415% across the stellar disk), this world measures 2.09 Earth radii and has a measured mass of 109.8 Earth masses (0.35 Jupiter masses). Combining its mass and radius yields a mean bulk density of 66.32 g/cm³ (an iron-enriched, high-compression rocky core), a surface gravity of 25.14 g⊕ (246.54 m/s²), and an escape velocity of 81.1 km/s.
In its orbital architecture around Kepler-317, Kepler-317 b completes one full revolution every 5.524 Earth days at a semi-major axis of 0.061 AU (orbiting interior to Mercury's 0.387 AU benchmark in the Solar System). Its mean orbital velocity is approximately 120.1 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 976 K (+703°C / +1297°F) and receiving 151.65 S⊕ (~206,398 W/m²), Kepler-317 b orbits interior to the runaway greenhouse boundary where surface liquid water cannot persist.
The host star Kepler-317 is classified as a stellar host with an effective photospheric temperature of 5,497 K, a radius of 0.941 R☉, a mass of 0.865 M☉, an estimated bolometric luminosity of 0.725 L☉. Stellar evolution modeling indicates an estimated stellar age of 3.72 Gyr and a metallicity of [Fe/H] = 0.13 dex (metal-rich relative to the Sun). From Earth, Kepler-317 shines at apparent V-band magnitude 15.665 (faint and requiring research-grade or CCD telescopic photometry) in the Northern celestial hemisphere. The Kepler-317 system is a multi-planet architecture hosting 2 confirmed worlds, with Kepler-317 b sharing its stellar neighborhood alongside Kepler-317 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-317 |
| Spectral Type | Unclassified |
| Effective Temp (Teff) | 5,497 K |
| Stellar Radius | 0.9410 R☉ |
| Stellar Mass | 0.8650 M☉ |
| Bolometric Luminosity | 0.725 L☉ |
| Metallicity [Fe/H] | 0.130 dex |
| Stellar Age | 3.720 Gyr |
| Apparent Magnitude | V: 15.665 · G: 15.457 |
| System Architecture | 1 Star, 2 Planets |
🪐 Orbital & Physical Dynamics
| Semi-Major Axis (a) | 0.061000 AU |
| Orbital Period | 5.524 days |
| Mean Orbital Velocity | 120.1 km/s |
| Orbital Eccentricity (e) | 0.00000 |
| Orbital Inclination (i) | 87.8900° |
| Mean Bulk Density | 66.32 g/cm³ (81.1 km/s vesc) |
| Insolation Flux | 151.6520 S⊕ (~206,398 W/m²) |
| Habitable Zone Status | Exterior / Non-HZ |
| Celestial Distance | 3067.800 LY (940.584 pc) |