Kepler-102 d
Astrophysical Synthesis & Habitability Characterization
Kepler-102 d is a confirmed terrestrial exoplanet orbiting the star Kepler-102, located approximately 351.6 light-years (107.8 parsecs) from the Solar System. First announced in 2014 by Kepler using the Transit detection technique (producing an estimated primary transit depth of 0.0214% across the stellar disk), this world measures 1.154 Earth radii and has a measured mass of 3 Earth masses. Combining its mass and radius yields a mean bulk density of 10.76 g/cm³ (an iron-enriched, high-compression rocky core), a surface gravity of 2.25 g⊕ (22.06 m/s²), and an escape velocity of 18 km/s.
In its orbital architecture around Kepler-102, Kepler-102 d completes one full revolution every 10.312 Earth days at a semi-major axis of 0.08618 AU (orbiting interior to Mercury's 0.387 AU benchmark in the Solar System). Its mean orbital velocity is approximately 90.9 km/s (compared to Earth's 29.8 km/s). Its moderate orbital eccentricity of e = 0.092 carries the world between 0.0783 AU at periapsis and 0.0941 AU at apoapsis, driving measurable seasonal insolation cycles.
⚠️ Thermal Regime (Irradiated / Hot Zone): At an equilibrium temperature of 686 K (+413°C / +775°F) and receiving 36.90 S⊕ (~50,221 W/m²), Kepler-102 d orbits interior to the runaway greenhouse boundary where surface liquid water cannot persist.
The host star Kepler-102 is classified as a stellar host with an effective photospheric temperature of 4,909 K, a radius of 0.724 R☉, a mass of 0.803 M☉, an estimated bolometric luminosity of 0.273 L☉. Stellar evolution modeling indicates an estimated stellar age of 1.1 Gyr and a metallicity of [Fe/H] = 0.11 dex (metal-rich relative to the Sun). From Earth, Kepler-102 shines at apparent V-band magnitude 12.072 (faint and requiring research-grade or CCD telescopic photometry) in the Northern celestial hemisphere. The Kepler-102 system is a multi-planet architecture hosting 5 confirmed worlds, with Kepler-102 d sharing its stellar neighborhood alongside Kepler-102 b, Kepler-102 c, Kepler-102 e, Kepler-102 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-102 |
| Spectral Type | Unclassified |
| Effective Temp (Teff) | 4,909 K |
| Stellar Radius | 0.7240 R☉ |
| Stellar Mass | 0.8030 M☉ |
| Bolometric Luminosity | 0.273 L☉ |
| Metallicity [Fe/H] | 0.110 dex |
| Stellar Age | 1.100 Gyr |
| Apparent Magnitude | V: 12.072 · G: 11.478 |
| System Architecture | 1 Star, 5 Planets |
🪐 Orbital & Physical Dynamics
| Semi-Major Axis (a) | 0.086180 AU |
| Orbital Period | 10.312 days |
| Mean Orbital Velocity | 90.9 km/s |
| Orbital Eccentricity (e) | 0.09200 |
| Orbital Inclination (i) | 89.4900° |
| Mean Bulk Density | 10.76 g/cm³ (18 km/s vesc) |
| Insolation Flux | 36.9000 S⊕ (~50,221 W/m²) |
| Habitable Zone Status | Exterior / Non-HZ |
| Celestial Distance | 351.600 LY (107.796 pc) |