Kepler-186 f
Astrophysical Synthesis & Habitability Characterization
Kepler-186 f is a confirmed terrestrial exoplanet orbiting the star Kepler-186, located approximately 579.2 light-years (177.59 parsecs) from the Solar System. First announced in 2014 by Kepler using the Transit detection technique (producing an estimated primary transit depth of 0.0421% across the stellar disk), this world measures 1.17 Earth radii and has a measured mass of 1.71 Earth masses. Combining its mass and radius yields a mean bulk density of 5.89 g/cm³ (a terrestrial silicate-iron composition comparable to Earth (5.51 g/cm³)), a surface gravity of 1.25 g⊕ (12.26 m/s²), and an escape velocity of 13.5 km/s.
In its orbital architecture around Kepler-186, Kepler-186 f completes one full revolution every 129.944 Earth days at a semi-major axis of 0.432 AU (situated at an orbital separation between Mercury's 0.39 AU and Venus's 0.72 AU). Its mean orbital velocity is approximately 36.2 km/s (compared to Earth's 29.8 km/s). With a near-circular eccentricity of e = 0.04 (ranging from 0.4147 AU at periapsis to 0.4493 AU at apoapsis), the planet experiences minimal orbital distance variation.
❄️ Thermal Regime (Cryogenic Zone): With an equilibrium temperature of 177 K (-96°C / -141°F) and an incident flux of 0.30 S⊕ (~408 W/m²), surface water and volatile species on Kepler-186 f would remain locked in cryogenic ice phases unless warmed by subsurface tidal or radiogenic heating.
The host star Kepler-186 is classified as a low-mass red dwarf of spectral type M1 with an effective photospheric temperature of 3,755 K, a radius of 0.523 R☉, a mass of 0.544 M☉, an estimated bolometric luminosity of 0.049 L☉. Stellar evolution modeling indicates an estimated stellar age of 4 Gyr and a metallicity of [Fe/H] = -0.26 dex (metal-poor relative to the Sun). From Earth, Kepler-186 shines at apparent V-band magnitude 15.138 (faint and requiring research-grade or CCD telescopic photometry) in the Northern celestial hemisphere. The Kepler-186 system is a multi-planet architecture hosting 5 confirmed worlds, with Kepler-186 f sharing its stellar neighborhood alongside Kepler-186 b, Kepler-186 c, Kepler-186 d, Kepler-186 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-186 |
| Spectral Type | M1 |
| Effective Temp (Teff) | 3,755 K |
| Stellar Radius | 0.5230 R☉ |
| Stellar Mass | 0.5440 M☉ |
| Bolometric Luminosity | 0.049 L☉ |
| Metallicity [Fe/H] | -0.260 dex |
| Stellar Age | 4.000 Gyr |
| Apparent Magnitude | V: 15.138 · G: 14.599 |
| System Architecture | 1 Star, 5 Planets |
🪐 Orbital & Physical Dynamics
| Semi-Major Axis (a) | 0.432000 AU |
| Orbital Period | 129.944 days |
| Mean Orbital Velocity | 36.2 km/s |
| Orbital Eccentricity (e) | 0.04000 |
| Orbital Inclination (i) | 89.9600° |
| Mean Bulk Density | 5.89 g/cm³ (13.5 km/s vesc) |
| Insolation Flux | 0.3000 S⊕ (~408 W/m²) |
| Habitable Zone Status | Exterior / Non-HZ |
| Celestial Distance | 579.200 LY (177.594 pc) |