Kepler-1218 b
Astrophysical Synthesis & Habitability Characterization
Kepler-1218 b is a confirmed super-earth exoplanet orbiting the star Kepler-1218, located approximately 2741.4 light-years (840.5 parsecs) from the Solar System. First announced in 2016 by Kepler using the Transit detection technique (producing an estimated primary transit depth of 0.0144% across the stellar disk), this world measures 1.44 Earth radii and has a measured mass of 2.67 Earth masses. Combining its mass and radius yields a mean bulk density of 4.93 g/cm³ (a terrestrial silicate-iron composition comparable to Earth (5.51 g/cm³)), a surface gravity of 1.29 g⊕ (12.65 m/s²), and an escape velocity of 15.2 km/s.
In its orbital architecture around Kepler-1218, Kepler-1218 b completes one full revolution every 22.922 Earth days at a semi-major axis of 0.15698 AU (orbiting interior to Mercury's 0.387 AU benchmark in the Solar System). Its mean orbital velocity is approximately 74.5 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 684 K (+411°C / +772°F) and receiving 84.83 S⊕ (~115,454 W/m²), Kepler-1218 b orbits interior to the runaway greenhouse boundary where surface liquid water cannot persist.
The host star Kepler-1218 is classified as a stellar host with an effective photospheric temperature of 5,986 K, a radius of 1.1 R☉, a mass of 1.06 M☉, an estimated bolometric luminosity of 1.394 L☉. Stellar evolution modeling indicates an estimated stellar age of 3.8 Gyr and a metallicity of [Fe/H] = -0.02 dex (near-solar heavy-element abundance). From Earth, Kepler-1218 shines at apparent V-band magnitude 13.73 (faint and requiring research-grade or CCD telescopic photometry) in the Northern celestial hemisphere.
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-1218 |
| Spectral Type | Unclassified |
| Effective Temp (Teff) | 5,986 K |
| Stellar Radius | 1.1000 R☉ |
| Stellar Mass | 1.0600 M☉ |
| Bolometric Luminosity | 1.394 L☉ |
| Metallicity [Fe/H] | -0.020 dex |
| Stellar Age | 3.800 Gyr |
| Apparent Magnitude | V: 13.730 · G: 13.551 |
| System Architecture | 1 Star, 1 Planet |
🪐 Orbital & Physical Dynamics
| Semi-Major Axis (a) | 0.156980 AU |
| Orbital Period | 22.922 days |
| Mean Orbital Velocity | 74.5 km/s |
| Orbital Eccentricity (e) | 0.00000 |
| Orbital Inclination (i) | 88.0100° |
| Mean Bulk Density | 4.93 g/cm³ (15.2 km/s vesc) |
| Insolation Flux | 84.8300 S⊕ (~115,454 W/m²) |
| Habitable Zone Status | Exterior / Non-HZ |
| Celestial Distance | 2741.400 LY (840.503 pc) |