Kepler-1311 c
Astrophysical Synthesis & Habitability Characterization
Kepler-1311 c is a confirmed terrestrial exoplanet orbiting the star Kepler-1311, located approximately 2825.6 light-years (866.33 parsecs) from the Solar System. First announced in 2016 by Kepler using the Transit detection technique (producing an estimated primary transit depth of 0.0064% across the stellar disk), this world measures 1.22 Earth radii and has a measured mass of 1.98 Earth masses. Combining its mass and radius yields a mean bulk density of 6.01 g/cm³ (a terrestrial silicate-iron composition comparable to Earth (5.51 g/cm³)), a surface gravity of 1.33 g⊕ (13.04 m/s²), and an escape velocity of 14.3 km/s.
In its orbital architecture around Kepler-1311, Kepler-1311 c completes one full revolution every 2.536 Earth days at a semi-major axis of 0.03753 AU (an ultra-close orbit less than one-seventh of Mercury's 0.387 AU distance from the Sun, where strong stellar tidal forces typically induce synchronous rotation). Its mean orbital velocity is approximately 161 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 1671 K (+1398°C / +2548°F) and receiving 2,144.55 S⊕ (~2,918,737 W/m²), Kepler-1311 c orbits interior to the runaway greenhouse boundary where surface liquid water cannot persist.
The host star Kepler-1311 is classified as a stellar host with an effective photospheric temperature of 5,748 K, a radius of 1.4 R☉, a mass of 1.05 M☉, an estimated bolometric luminosity of 1.92 L☉. Stellar evolution modeling indicates an estimated stellar age of 7.59 Gyr and a metallicity of [Fe/H] = 0.09 dex (metal-rich relative to the Sun). From Earth, Kepler-1311 shines at apparent V-band magnitude 13.528 (faint and requiring research-grade or CCD telescopic photometry) in the Northern celestial hemisphere. The Kepler-1311 system is a multi-planet architecture hosting 3 confirmed worlds, with Kepler-1311 c sharing its stellar neighborhood alongside Kepler-1311 b, Kepler-1311 d.
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-1311 |
| Spectral Type | Unclassified |
| Effective Temp (Teff) | 5,748 K |
| Stellar Radius | 1.4000 R☉ |
| Stellar Mass | 1.0500 M☉ |
| Bolometric Luminosity | 1.92 L☉ |
| Metallicity [Fe/H] | 0.090 dex |
| Stellar Age | 7.590 Gyr |
| Apparent Magnitude | V: 13.528 · G: 13.318 |
| System Architecture | 1 Star, 3 Planets |
🪐 Orbital & Physical Dynamics
| Semi-Major Axis (a) | 0.037530 AU |
| Orbital Period | 2.536 days |
| Mean Orbital Velocity | 161 km/s |
| Orbital Eccentricity (e) | 0.00000 |
| Orbital Inclination (i) | 89.3700° |
| Mean Bulk Density | 6.01 g/cm³ (14.3 km/s vesc) |
| Insolation Flux | 2144.5530 S⊕ (~2,918,737 W/m²) |
| Habitable Zone Status | Exterior / Non-HZ |
| Celestial Distance | 2825.600 LY (866.331 pc) |