Kepler-107 d
Astrophysical Synthesis & Habitability Characterization
Kepler-107 d is a confirmed terrestrial exoplanet orbiting the star Kepler-107, located approximately 1715.6 light-years (526 parsecs) from the Solar System. First announced in 2014 by Kepler using the Transit detection technique (producing an estimated primary transit depth of 0.003% across the stellar disk), this world measures 0.86 Earth radii and has a measured mass of 7.7 Earth masses. Combining its mass and radius yields a mean bulk density of 66.75 g/cm³ (an iron-enriched, high-compression rocky core), a surface gravity of 10.41 g⊕ (102.09 m/s²), and an escape velocity of 33.5 km/s.
In its orbital architecture around Kepler-107, Kepler-107 d completes one full revolution every 7.958 Earth days at a semi-major axis of 0.08377 AU (orbiting interior to Mercury's 0.387 AU benchmark in the Solar System). Its mean orbital velocity is approximately 114.5 km/s (compared to Earth's 29.8 km/s). Its moderate orbital eccentricity of e = 0.11 carries the world between 0.0746 AU at periapsis and 0.093 AU at apoapsis, driving measurable seasonal insolation cycles.
⚠️ Thermal Regime (Irradiated / Hot Zone): At an equilibrium temperature of 1173 K (+900°C / +1652°F) and receiving 315.00 S⊕ (~428,715 W/m²), Kepler-107 d orbits interior to the runaway greenhouse boundary where surface liquid water cannot persist.
The host star Kepler-107 is classified as a stellar host with an effective photospheric temperature of 5,854 K, a radius of 1.447 R☉, a mass of 1.238 M☉, an estimated bolometric luminosity of 2.206 L☉. Stellar evolution modeling indicates an estimated stellar age of 4.29 Gyr and a metallicity of [Fe/H] = 0.321 dex (metal-rich relative to the Sun). From Earth, Kepler-107 shines at apparent V-band magnitude 12.543 (faint and requiring research-grade or CCD telescopic photometry) in the Northern celestial hemisphere. The Kepler-107 system is a multi-planet architecture hosting 4 confirmed worlds, with Kepler-107 d sharing its stellar neighborhood alongside Kepler-107 b, Kepler-107 c, Kepler-107 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-107 |
| Spectral Type | Unclassified |
| Effective Temp (Teff) | 5,854 K |
| Stellar Radius | 1.4470 R☉ |
| Stellar Mass | 1.2380 M☉ |
| Bolometric Luminosity | 2.206 L☉ |
| Metallicity [Fe/H] | 0.321 dex |
| Stellar Age | 4.290 Gyr |
| Apparent Magnitude | V: 12.543 · G: 12.463 |
| System Architecture | 1 Star, 4 Planets |
🪐 Orbital & Physical Dynamics
| Semi-Major Axis (a) | 0.083770 AU |
| Orbital Period | 7.958 days |
| Mean Orbital Velocity | 114.5 km/s |
| Orbital Eccentricity (e) | 0.11000 |
| Orbital Inclination (i) | 87.5500° |
| Mean Bulk Density | 66.75 g/cm³ (33.5 km/s vesc) |
| Insolation Flux | 315.0000 S⊕ (~428,715 W/m²) |
| Habitable Zone Status | Exterior / Non-HZ |
| Celestial Distance | 1715.600 LY (525.997 pc) |