Kepler-247 c
Astrophysical Synthesis & Habitability Characterization
Kepler-247 c is a confirmed sub-neptune exoplanet orbiting the star Kepler-247, located approximately 2164.7 light-years (663.71 parsecs) from the Solar System. First announced in 2014 by Kepler using the Transit detection technique (producing an estimated primary transit depth of 0.2384% across the stellar disk), this world measures 4.09 Earth radii (0.36 Jupiter radii) and has a measured mass of 15.7 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-247, Kepler-247 c completes one full revolution every 9.439 Earth days at a semi-major axis of 0.084 AU (orbiting interior to Mercury's 0.387 AU benchmark in the Solar System). Its mean orbital velocity is approximately 96.8 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 686 K (+413°C / +775°F) and receiving 53.90 S⊕ (~73,357 W/m²), Kepler-247 c orbits interior to the runaway greenhouse boundary where surface liquid water cannot persist.
The host star Kepler-247 is classified as an orange K-type star of spectral type K with an effective photospheric temperature of 5,100 K, a radius of 0.768 R☉, a mass of 0.887 M☉, an estimated bolometric luminosity of 0.358 L☉. Stellar evolution modeling indicates an estimated stellar age of 2.14 Gyr and a metallicity of [Fe/H] = 0.3 dex (metal-rich relative to the Sun). From Earth, Kepler-247 shines at apparent V-band magnitude 15.199 (faint and requiring research-grade or CCD telescopic photometry) in the Northern celestial hemisphere. The Kepler-247 system is a multi-planet architecture hosting 4 confirmed worlds, with Kepler-247 c sharing its stellar neighborhood alongside Kepler-247 b, Kepler-247 d, KOI-884 e.
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-247 |
| Spectral Type | K |
| Effective Temp (Teff) | 5,100 K |
| Stellar Radius | 0.7680 R☉ |
| Stellar Mass | 0.8870 M☉ |
| Bolometric Luminosity | 0.358 L☉ |
| Metallicity [Fe/H] | 0.300 dex |
| Stellar Age | 2.140 Gyr |
| Apparent Magnitude | V: 15.199 · G: 15.047 |
| System Architecture | 1 Star, 4 Planets |
🪐 Orbital & Physical Dynamics
| Semi-Major Axis (a) | 0.084000 AU |
| Orbital Period | 9.439 days |
| Mean Orbital Velocity | 96.8 km/s |
| Orbital Eccentricity (e) | 0.00000 |
| Orbital Inclination (i) | 89.8900° |
| Mean Bulk Density | 1.27 g/cm³ (21.9 km/s vesc) |
| Insolation Flux | 53.8990 S⊕ (~73,357 W/m²) |
| Habitable Zone Status | Exterior / Non-HZ |
| Celestial Distance | 2164.700 LY (663.711 pc) |