Kepler-19 c
Astrophysical Synthesis & Habitability Characterization
Kepler-19 c is a confirmed sub-neptune exoplanet orbiting the star Kepler-19, located approximately 712.9 light-years (218.56 parsecs) from the Solar System. First announced in 2011 by Kepler using the Transit Timing Variations detection technique (producing an estimated primary transit depth of 0.1543% across the stellar disk), this world measures 3.68 Earth radii (0.33 Jupiter radii) and has a measured mass of 13.1 Earth masses. Combining its mass and radius yields a mean bulk density of 1.45 g/cm³ (a low bulk density dominated by an extended hydrogen-helium gaseous envelope), a surface gravity of 0.97 g⊕ (9.51 m/s²), and an escape velocity of 21.1 km/s.
In its orbital architecture around Kepler-19, Kepler-19 c completes one full revolution every 28.731 Earth days at a semi-major axis of 0.176574 AU (orbiting interior to Mercury's 0.387 AU benchmark in the Solar System). Its mean orbital velocity is approximately 66.9 km/s (compared to Earth's 29.8 km/s). Its moderate orbital eccentricity of e = 0.21 carries the world between 0.1395 AU at periapsis and 0.2137 AU at apoapsis, driving measurable seasonal insolation cycles.
⚠️ Thermal Regime (Irradiated / Hot Zone): At an equilibrium temperature of 590 K (+317°C / +603°F) and receiving 22.16 S⊕ (~30,161 W/m²), Kepler-19 c orbits interior to the runaway greenhouse boundary where surface liquid water cannot persist.
The host star Kepler-19 is classified as a stellar host with an effective photospheric temperature of 5,544 K, a radius of 0.859 R☉, a mass of 0.936 M☉, an estimated bolometric luminosity of 0.625 L☉. Stellar evolution modeling indicates an estimated stellar age of 1.9 Gyr and a metallicity of [Fe/H] = -0.08 dex (near-solar heavy-element abundance). From Earth, Kepler-19 shines at apparent V-band magnitude 12.035 (faint and requiring research-grade or CCD telescopic photometry) in the Northern celestial hemisphere. The Kepler-19 system is a multi-planet architecture hosting 3 confirmed worlds, with Kepler-19 c sharing its stellar neighborhood alongside Kepler-19 b, Kepler-19 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-19 |
| Spectral Type | Unclassified |
| Effective Temp (Teff) | 5,544 K |
| Stellar Radius | 0.8590 R☉ |
| Stellar Mass | 0.9360 M☉ |
| Bolometric Luminosity | 0.625 L☉ |
| Metallicity [Fe/H] | -0.080 dex |
| Stellar Age | 1.900 Gyr |
| Apparent Magnitude | V: 12.035 · G: 11.876 |
| System Architecture | 1 Star, 3 Planets |
🪐 Orbital & Physical Dynamics
| Semi-Major Axis (a) | 0.176574 AU |
| Orbital Period | 28.731 days |
| Mean Orbital Velocity | 66.9 km/s |
| Orbital Eccentricity (e) | 0.21000 |
| Orbital Inclination (i) | — |
| Mean Bulk Density | 1.45 g/cm³ (21.1 km/s vesc) |
| Insolation Flux | 22.1608 S⊕ (~30,161 W/m²) |
| Habitable Zone Status | Exterior / Non-HZ |
| Celestial Distance | 712.900 LY (218.562 pc) |