Kepler-82 c
Astrophysical Synthesis & Habitability Characterization
Kepler-82 c is a confirmed sub-neptune exoplanet orbiting the star Kepler-82, located approximately 2949.5 light-years (904.33 parsecs) from the Solar System. First announced in 2012 by Kepler using the Transit detection technique (producing an estimated primary transit depth of 0.2972% across the stellar disk), this world measures 5.34 Earth radii (0.48 Jupiter radii) and has a measured mass of 13.9 Earth masses. Combining its mass and radius yields a mean bulk density of 0.5 g/cm³ (a low bulk density dominated by an extended hydrogen-helium gaseous envelope), a surface gravity of 0.49 g⊕ (4.81 m/s²), and an escape velocity of 18 km/s.
In its orbital architecture around Kepler-82, Kepler-82 c completes one full revolution every 51.54 Earth days at a semi-major axis of 0.2626 AU (orbiting interior to Mercury's 0.387 AU benchmark in the Solar System). Its mean orbital velocity is approximately 55.4 km/s (compared to Earth's 29.8 km/s). With a near-circular eccentricity of e = 0.007 (ranging from 0.2608 AU at periapsis to 0.2644 AU at apoapsis), the planet experiences minimal orbital distance variation.
⚠️ Thermal Regime (Irradiated / Hot Zone): At an equilibrium temperature of 450 K (+177°C / +351°F) and receiving 8.04 S⊕ (~10,936 W/m²), Kepler-82 c orbits interior to the runaway greenhouse boundary where surface liquid water cannot persist.
The host star Kepler-82 is classified as a solar-type yellow star of spectral type G with an effective photospheric temperature of 5,401 K, a radius of 0.898 R☉, a mass of 0.91 M☉, an estimated bolometric luminosity of 0.616 L☉. Stellar evolution modeling indicates an estimated stellar age of 1.41 Gyr and a metallicity of [Fe/H] = 0.211 dex (metal-rich relative to the Sun). From Earth, Kepler-82 shines at apparent V-band magnitude 15.131 (faint and requiring research-grade or CCD telescopic photometry) in the Northern celestial hemisphere. The Kepler-82 system is a multi-planet architecture hosting 5 confirmed worlds, with Kepler-82 c sharing its stellar neighborhood alongside Kepler-82 d, Kepler-82 e, Kepler-82 b, Kepler-82 f.
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-82 |
| Spectral Type | G |
| Effective Temp (Teff) | 5,401 K |
| Stellar Radius | 0.8980 R☉ |
| Stellar Mass | 0.9100 M☉ |
| Bolometric Luminosity | 0.616 L☉ |
| Metallicity [Fe/H] | 0.211 dex |
| Stellar Age | 1.410 Gyr |
| Apparent Magnitude | V: 15.131 · G: 15.138 |
| System Architecture | 1 Star, 5 Planets |
🪐 Orbital & Physical Dynamics
| Semi-Major Axis (a) | 0.262600 AU |
| Orbital Period | 51.54 days |
| Mean Orbital Velocity | 55.4 km/s |
| Orbital Eccentricity (e) | 0.00700 |
| Orbital Inclination (i) | 90.1500° |
| Mean Bulk Density | 0.5 g/cm³ (18 km/s vesc) |
| Insolation Flux | 8.0350 S⊕ (~10,936 W/m²) |
| Habitable Zone Status | Exterior / Non-HZ |
| Celestial Distance | 2949.500 LY (904.326 pc) |