Kepler-82 d
Astrophysical Synthesis & Habitability Characterization
Kepler-82 d is a confirmed super-earth exoplanet orbiting the star Kepler-82, located approximately 2949.5 light-years (904.33 parsecs) from the Solar System. First announced in 2014 by Kepler using the Transit detection technique (producing an estimated primary transit depth of 0.0295% across the stellar disk), this world measures 1.77 Earth radii and has a measured mass of 885.098 Earth masses (2.78 Jupiter masses). Combining its mass and radius yields a mean bulk density of 880.11 g/cm³ (an iron-enriched, high-compression rocky core), a surface gravity of 282.52 g⊕ (2770.57 m/s²), and an escape velocity of 250.1 km/s.
In its orbital architecture around Kepler-82, Kepler-82 d completes one full revolution every 2.383 Earth days at a semi-major axis of 0.034 AU (an ultra-close orbit less than one-seventh of Mercury's 0.387 AU distance from the Sun, where strong stellar tidal forces typically induce synchronous rotation). Its mean orbital velocity is approximately 155.2 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 1253 K (+980°C / +1796°F) and receiving 484.35 S⊕ (~659,202 W/m²), Kepler-82 d 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 5,428 K, a radius of 0.945 R☉, a mass of 0.946 M☉, an estimated bolometric luminosity of 0.696 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 d sharing its stellar neighborhood alongside Kepler-82 e, Kepler-82 b, Kepler-82 c, 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) | 5,428 K |
| Stellar Radius | 0.9450 R☉ |
| Stellar Mass | 0.9460 M☉ |
| Bolometric Luminosity | 0.696 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) | 0.034000 AU |
| Orbital Period | 2.383 days |
| Mean Orbital Velocity | 155.2 km/s |
| Orbital Eccentricity (e) | 0.00000 |
| Orbital Inclination (i) | 86.8500° |
| Mean Bulk Density | 880.11 g/cm³ (250.1 km/s vesc) |
| Insolation Flux | 484.3510 S⊕ (~659,202 W/m²) |
| Habitable Zone Status | Exterior / Non-HZ |
| Celestial Distance | 2949.500 LY (904.326 pc) |