Kepler-85 d
Astrophysical Synthesis & Habitability Characterization
Kepler-85 d is a confirmed terrestrial exoplanet orbiting the star Kepler-85, located approximately 2495.2 light-years (765.03 parsecs) from the Solar System. First announced in 2014 by Kepler using the Transit detection technique (producing an estimated primary transit depth of 0.0152% across the stellar disk), this world measures 1.2 Earth radii and has a measured mass of 8.697 Earth masses. Combining its mass and radius yields a mean bulk density of 27.75 g/cm³ (an iron-enriched, high-compression rocky core), a surface gravity of 6.04 g⊕ (59.23 m/s²), and an escape velocity of 30.1 km/s.
In its orbital architecture around Kepler-85, Kepler-85 d completes one full revolution every 17.913 Earth days at a semi-major axis of 0.13 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 626 K (+353°C / +667°F) and receiving 38.39 S⊕ (~52,249 W/m²), Kepler-85 d orbits interior to the runaway greenhouse boundary where surface liquid water cannot persist.
The host star Kepler-85 is classified as a stellar host with an effective photospheric temperature of 5,436 K, a radius of 0.893 R☉, a mass of 0.947 M☉, an estimated bolometric luminosity of 0.625 L☉. Stellar evolution modeling indicates an estimated stellar age of 1.38 Gyr and a metallicity of [Fe/H] = 0.12 dex (metal-rich relative to the Sun). From Earth, Kepler-85 shines at apparent V-band magnitude 14.89 (faint and requiring research-grade or CCD telescopic photometry) in the Northern celestial hemisphere. The Kepler-85 system is a multi-planet architecture hosting 4 confirmed worlds, with Kepler-85 d sharing its stellar neighborhood alongside Kepler-85 b, Kepler-85 c, Kepler-85 e.
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-85 |
| Spectral Type | Unclassified |
| Effective Temp (Teff) | 5,436 K |
| Stellar Radius | 0.8930 R☉ |
| Stellar Mass | 0.9470 M☉ |
| Bolometric Luminosity | 0.625 L☉ |
| Metallicity [Fe/H] | 0.120 dex |
| Stellar Age | 1.380 Gyr |
| Apparent Magnitude | V: 14.890 · G: 14.766 |
| System Architecture | 1 Star, 4 Planets |
🪐 Orbital & Physical Dynamics
| Semi-Major Axis (a) | 0.130000 AU |
| Orbital Period | 17.913 days |
| Mean Orbital Velocity | 79 km/s |
| Orbital Eccentricity (e) | 0.00000 |
| Orbital Inclination (i) | 87.3900° |
| Mean Bulk Density | 27.75 g/cm³ (30.1 km/s vesc) |
| Insolation Flux | 38.3900 S⊕ (~52,249 W/m²) |
| Habitable Zone Status | Exterior / Non-HZ |
| Celestial Distance | 2495.200 LY (765.025 pc) |