Kepler-417 c
Astrophysical Synthesis & Habitability Characterization
Kepler-417 c is a confirmed sub-neptune exoplanet orbiting the star Kepler-417, located approximately 3176.7 light-years (973.99 parsecs) from the Solar System. First announced in 2014 by Kepler using the Transit detection technique (producing an estimated primary transit depth of 0.0936% across the stellar disk), this world measures 2.69 Earth radii and has a measured mass of 7.7 Earth masses. Combining its mass and radius yields a mean bulk density of 2.18 g/cm³ (an intermediate density indicative of a deep water-ice mantle or dense volatile envelope), a surface gravity of 1.06 g⊕ (10.4 m/s²), and an escape velocity of 18.9 km/s.
In its orbital architecture around Kepler-417, Kepler-417 c completes one full revolution every 15.943 Earth days at a semi-major axis of 0.1194 AU (orbiting interior to Mercury's 0.387 AU benchmark in the Solar System). Its mean orbital velocity is approximately 81.5 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 616 K (+343°C / +649°F) and receiving 30.97 S⊕ (~42,147 W/m²), Kepler-417 c orbits interior to the runaway greenhouse boundary where surface liquid water cannot persist.
The host star Kepler-417 is classified as a stellar host with an effective photospheric temperature of 5,177 K, a radius of 0.806 R☉, a mass of 0.9 M☉, an estimated bolometric luminosity of 0.419 L☉. Stellar evolution modeling indicates an estimated stellar age of 4.9 Gyr and a metallicity of [Fe/H] = -0.204 dex (metal-poor relative to the Sun). From Earth, Kepler-417 shines at apparent V-band magnitude 15.864 (faint and requiring research-grade or CCD telescopic photometry) in the Northern celestial hemisphere. The Kepler-417 system is a multi-planet architecture hosting 2 confirmed worlds, with Kepler-417 c sharing its stellar neighborhood alongside Kepler-417 b.
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-417 |
| Spectral Type | Unclassified |
| Effective Temp (Teff) | 5,177 K |
| Stellar Radius | 0.8060 R☉ |
| Stellar Mass | 0.9000 M☉ |
| Bolometric Luminosity | 0.419 L☉ |
| Metallicity [Fe/H] | -0.204 dex |
| Stellar Age | 4.900 Gyr |
| Apparent Magnitude | V: 15.864 · G: 15.866 |
| System Architecture | 1 Star, 2 Planets |
🪐 Orbital & Physical Dynamics
| Semi-Major Axis (a) | 0.119400 AU |
| Orbital Period | 15.943 days |
| Mean Orbital Velocity | 81.5 km/s |
| Orbital Eccentricity (e) | 0.00000 |
| Orbital Inclination (i) | 89.9600° |
| Mean Bulk Density | 2.18 g/cm³ (18.9 km/s vesc) |
| Insolation Flux | 30.9680 S⊕ (~42,147 W/m²) |
| Habitable Zone Status | Exterior / Non-HZ |
| Celestial Distance | 3176.700 LY (973.989 pc) |