Kepler-647 c
Astrophysical Synthesis & Habitability Characterization
Kepler-647 c is a confirmed sub-neptune exoplanet orbiting the star Kepler-647, located approximately 3548.2 light-years (1087.87 parsecs) from the Solar System. First announced in 2020 by Kepler using the Transit detection technique (producing an estimated primary transit depth of 0.0563% across the stellar disk), this world measures 4.001 Earth radii (0.36 Jupiter radii) and has a measured mass of 15.1 Earth masses. Combining its mass and radius yields a mean bulk density of 1.3 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 21.7 km/s.
In its orbital architecture around Kepler-647, Kepler-647 c completes one full revolution every 29.666 Earth days at a semi-major axis of 0.18291 AU (orbiting interior to Mercury's 0.387 AU benchmark in the Solar System). Its mean orbital velocity is approximately 67.1 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 644 K (+371°C / +700°F) and receiving 69.00 S⊕ (~93,909 W/m²), Kepler-647 c orbits interior to the runaway greenhouse boundary where surface liquid water cannot persist.
The host star Kepler-647 is classified as a stellar host with an effective photospheric temperature of 5,907 K, a radius of 1.5457 R☉, a mass of 1.07 M☉, an estimated bolometric luminosity of 2.61 L☉. Stellar evolution modeling indicates an estimated stellar age of 2.75 Gyr and a metallicity of [Fe/H] = -0.415 dex (metal-poor relative to the Sun). From Earth, Kepler-647 shines at apparent V-band magnitude 14.067 (faint and requiring research-grade or CCD telescopic photometry) in the Northern celestial hemisphere. The Kepler-647 system is a multi-planet architecture hosting 2 confirmed worlds, with Kepler-647 c sharing its stellar neighborhood alongside Kepler-647 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-647 |
| Spectral Type | Unclassified |
| Effective Temp (Teff) | 5,907 K |
| Stellar Radius | 1.5457 R☉ |
| Stellar Mass | 1.0700 M☉ |
| Bolometric Luminosity | 2.61 L☉ |
| Metallicity [Fe/H] | -0.415 dex |
| Stellar Age | 2.750 Gyr |
| Apparent Magnitude | V: 14.067 · G: 13.935 |
| System Architecture | 1 Star, 2 Planets |
🪐 Orbital & Physical Dynamics
| Semi-Major Axis (a) | 0.182910 AU |
| Orbital Period | 29.666 days |
| Mean Orbital Velocity | 67.1 km/s |
| Orbital Eccentricity (e) | 0.00000 |
| Orbital Inclination (i) | 89.9600° |
| Mean Bulk Density | 1.3 g/cm³ (21.7 km/s vesc) |
| Insolation Flux | 69.0000 S⊕ (~93,909 W/m²) |
| Habitable Zone Status | Exterior / Non-HZ |
| Celestial Distance | 3548.200 LY (1087.870 pc) |