Kepler-92 d
Astrophysical Synthesis & Habitability Characterization
Kepler-92 d is a confirmed sub-neptune exoplanet orbiting the star Kepler-92, located approximately 1559 light-years (477.99 parsecs) from the Solar System. First announced in 2015 by Kepler using the Transit detection technique (producing an estimated primary transit depth of 0.0109% across the stellar disk), this world measures 2.067 Earth radii and has a measured mass of 11.867 Earth masses. Combining its mass and radius yields a mean bulk density of 7.41 g/cm³ (an iron-enriched, high-compression rocky core), a surface gravity of 2.78 g⊕ (27.26 m/s²), and an escape velocity of 26.8 km/s.
In its orbital architecture around Kepler-92, Kepler-92 d completes one full revolution every 49.357 Earth days at a semi-major axis of 0.28682 AU (orbiting interior to Mercury's 0.387 AU benchmark in the Solar System). Its mean orbital velocity is approximately 63.2 km/s (compared to Earth's 29.8 km/s). Its moderate orbital eccentricity of e = 0.07 carries the world between 0.2667 AU at periapsis and 0.3069 AU at apoapsis, driving measurable seasonal insolation cycles.
⚠️ Thermal Regime (Irradiated / Hot Zone): At an equilibrium temperature of 637 K (+364°C / +687°F) and receiving 46.84 S⊕ (~63,755 W/m²), Kepler-92 d orbits interior to the runaway greenhouse boundary where surface liquid water cannot persist.
The host star Kepler-92 is classified as a stellar host with an effective photospheric temperature of 5,904 K, a radius of 1.8172 R☉, a mass of 1.07 M☉, an estimated bolometric luminosity of 3.6 L☉. Stellar evolution modeling indicates an estimated stellar age of 3.98 Gyr and a metallicity of [Fe/H] = 0.138 dex (metal-rich relative to the Sun). From Earth, Kepler-92 shines at apparent V-band magnitude 11.671 (faint and requiring research-grade or CCD telescopic photometry) in the Northern celestial hemisphere. The Kepler-92 system is a multi-planet architecture hosting 3 confirmed worlds, with Kepler-92 d sharing its stellar neighborhood alongside Kepler-92 b, Kepler-92 c.
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-92 |
| Spectral Type | Unclassified |
| Effective Temp (Teff) | 5,904 K |
| Stellar Radius | 1.8172 R☉ |
| Stellar Mass | 1.0700 M☉ |
| Bolometric Luminosity | 3.6 L☉ |
| Metallicity [Fe/H] | 0.138 dex |
| Stellar Age | 3.980 Gyr |
| Apparent Magnitude | V: 11.671 · G: 11.745 |
| System Architecture | 1 Star, 3 Planets |
🪐 Orbital & Physical Dynamics
| Semi-Major Axis (a) | 0.286820 AU |
| Orbital Period | 49.357 days |
| Mean Orbital Velocity | 63.2 km/s |
| Orbital Eccentricity (e) | 0.07000 |
| Orbital Inclination (i) | 89.5300° |
| Mean Bulk Density | 7.41 g/cm³ (26.8 km/s vesc) |
| Insolation Flux | 46.8440 S⊕ (~63,755 W/m²) |
| Habitable Zone Status | Exterior / Non-HZ |
| Celestial Distance | 1559.000 LY (477.992 pc) |