Kepler-219 c
Astrophysical Synthesis & Habitability Characterization
Kepler-219 c is a confirmed sub-neptune exoplanet orbiting the star Kepler-219, located approximately 2567.1 light-years (787.07 parsecs) from the Solar System. First announced in 2014 by Kepler using the Transit detection technique (producing an estimated primary transit depth of 0.0485% across the stellar disk), this world measures 3.58 Earth radii (0.32 Jupiter radii) and has a measured mass of 12.5 Earth masses. Combining its mass and radius yields a mean bulk density of 1.5 g/cm³ (a low bulk density dominated by an extended hydrogen-helium gaseous envelope), a surface gravity of 0.98 g⊕ (9.61 m/s²), and an escape velocity of 20.9 km/s.
In its orbital architecture around Kepler-219, Kepler-219 c completes one full revolution every 22.715 Earth days at a semi-major axis of 0.165 AU (orbiting interior to Mercury's 0.387 AU benchmark in the Solar System). Its mean orbital velocity is approximately 79 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 766 K (+493°C / +919°F) and receiving 54.11 S⊕ (~73,637 W/m²), Kepler-219 c orbits interior to the runaway greenhouse boundary where surface liquid water cannot persist.
The host star Kepler-219 is classified as a stellar host with an effective photospheric temperature of 5,786 K, a radius of 1.491 R☉, a mass of 1.164 M☉, an estimated bolometric luminosity of 2.235 L☉. Stellar evolution modeling indicates an estimated stellar age of 4 Gyr and a metallicity of [Fe/H] = 0.36 dex (metal-rich relative to the Sun). From Earth, Kepler-219 shines at apparent V-band magnitude 13.823 (faint and requiring research-grade or CCD telescopic photometry) in the Northern celestial hemisphere. The Kepler-219 system is a multi-planet architecture hosting 3 confirmed worlds, with Kepler-219 c sharing its stellar neighborhood alongside Kepler-219 b, Kepler-219 d.
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-219 |
| Spectral Type | Unclassified |
| Effective Temp (Teff) | 5,786 K |
| Stellar Radius | 1.4910 R☉ |
| Stellar Mass | 1.1640 M☉ |
| Bolometric Luminosity | 2.235 L☉ |
| Metallicity [Fe/H] | 0.360 dex |
| Stellar Age | 4.000 Gyr |
| Apparent Magnitude | V: 13.823 · G: 13.718 |
| System Architecture | 1 Star, 3 Planets |
🪐 Orbital & Physical Dynamics
| Semi-Major Axis (a) | 0.165000 AU |
| Orbital Period | 22.715 days |
| Mean Orbital Velocity | 79 km/s |
| Orbital Eccentricity (e) | 0.00000 |
| Orbital Inclination (i) | 87.3600° |
| Mean Bulk Density | 1.5 g/cm³ (20.9 km/s vesc) |
| Insolation Flux | 54.1050 S⊕ (~73,637 W/m²) |
| Habitable Zone Status | Exterior / Non-HZ |
| Celestial Distance | 2567.100 LY (787.070 pc) |