Kepler-216 c
Astrophysical Synthesis & Habitability Characterization
Kepler-216 c is a confirmed sub-neptune exoplanet orbiting the star Kepler-216, located approximately 3873 light-years (1187.47 parsecs) from the Solar System. First announced in 2014 by Kepler using the Transit detection technique (producing an estimated primary transit depth of 0.0489% across the stellar disk), this world measures 3.04 Earth radii (0.27 Jupiter radii) and has a measured mass of 9.48 Earth masses. Combining its mass and radius yields a mean bulk density of 1.86 g/cm³ (a low bulk density dominated by an extended hydrogen-helium gaseous envelope), a surface gravity of 1.03 g⊕ (10.1 m/s²), and an escape velocity of 19.8 km/s.
In its orbital architecture around Kepler-216, Kepler-216 c completes one full revolution every 17.407 Earth days at a semi-major axis of 0.136 AU (orbiting interior to Mercury's 0.387 AU benchmark in the Solar System). Its mean orbital velocity is approximately 85 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 814 K (+541°C / +1006°F) and receiving 182.06 S⊕ (~247,780 W/m²), Kepler-216 c orbits interior to the runaway greenhouse boundary where surface liquid water cannot persist.
The host star Kepler-216 is classified as a stellar host with an effective photospheric temperature of 6,091 K, a radius of 1.26 R☉, a mass of 1.126 M☉, an estimated bolometric luminosity of 1.961 L☉. Stellar evolution modeling indicates an estimated stellar age of 0.28 Gyr and a metallicity of [Fe/H] = -0.149 dex (metal-poor relative to the Sun). From Earth, Kepler-216 shines at apparent V-band magnitude 14.054 (faint and requiring research-grade or CCD telescopic photometry) in the Northern celestial hemisphere. The Kepler-216 system is a multi-planet architecture hosting 2 confirmed worlds, with Kepler-216 c sharing its stellar neighborhood alongside Kepler-216 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-216 |
| Spectral Type | Unclassified |
| Effective Temp (Teff) | 6,091 K |
| Stellar Radius | 1.2600 R☉ |
| Stellar Mass | 1.1260 M☉ |
| Bolometric Luminosity | 1.961 L☉ |
| Metallicity [Fe/H] | -0.149 dex |
| Stellar Age | 0.280 Gyr |
| Apparent Magnitude | V: 14.054 · G: 13.961 |
| System Architecture | 1 Star, 2 Planets |
🪐 Orbital & Physical Dynamics
| Semi-Major Axis (a) | 0.136000 AU |
| Orbital Period | 17.407 days |
| Mean Orbital Velocity | 85 km/s |
| Orbital Eccentricity (e) | 0.00000 |
| Orbital Inclination (i) | 89.9400° |
| Mean Bulk Density | 1.86 g/cm³ (19.8 km/s vesc) |
| Insolation Flux | 182.0570 S⊕ (~247,780 W/m²) |
| Habitable Zone Status | Exterior / Non-HZ |
| Celestial Distance | 3873.000 LY (1187.470 pc) |