Kepler-211 b
Astrophysical Synthesis & Habitability Characterization
Kepler-211 b is a confirmed super-earth exoplanet orbiting the star Kepler-211, located approximately 1009 light-years (309.35 parsecs) from the Solar System. First announced in 2014 by Kepler using the Transit detection technique (producing an estimated primary transit depth of 0.02% across the stellar disk), this world measures 1.26 Earth radii and has a measured mass of 2.13 Earth masses. Combining its mass and radius yields a mean bulk density of 5.87 g/cm³ (a terrestrial silicate-iron composition comparable to Earth (5.51 g/cm³)), a surface gravity of 1.34 g⊕ (13.14 m/s²), and an escape velocity of 14.5 km/s.
In its orbital architecture around Kepler-211, Kepler-211 b completes one full revolution every 4.139 Earth days at a semi-major axis of 0.048 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 126.2 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 954 K (+681°C / +1258°F) and receiving 158.19 S⊕ (~215,294 W/m²), Kepler-211 b orbits interior to the runaway greenhouse boundary where surface liquid water cannot persist.
The host star Kepler-211 is classified as a stellar host with an effective photospheric temperature of 5,123 K, a radius of 0.816 R☉, a mass of 0.867 M☉, an estimated bolometric luminosity of 0.411 L☉. Stellar evolution modeling indicates an estimated stellar age of 1.55 Gyr and a metallicity of [Fe/H] = 0.151 dex (metal-rich relative to the Sun). From Earth, Kepler-211 shines at apparent V-band magnitude 13.448 (faint and requiring research-grade or CCD telescopic photometry) in the Northern celestial hemisphere. The Kepler-211 system is a multi-planet architecture hosting 2 confirmed worlds, with Kepler-211 b sharing its stellar neighborhood alongside Kepler-211 c.
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-211 |
| Spectral Type | Unclassified |
| Effective Temp (Teff) | 5,123 K |
| Stellar Radius | 0.8160 R☉ |
| Stellar Mass | 0.8670 M☉ |
| Bolometric Luminosity | 0.411 L☉ |
| Metallicity [Fe/H] | 0.151 dex |
| Stellar Age | 1.550 Gyr |
| Apparent Magnitude | V: 13.448 · G: 13.273 |
| System Architecture | 1 Star, 2 Planets |
🪐 Orbital & Physical Dynamics
| Semi-Major Axis (a) | 0.048000 AU |
| Orbital Period | 4.139 days |
| Mean Orbital Velocity | 126.2 km/s |
| Orbital Eccentricity (e) | 0.00000 |
| Orbital Inclination (i) | 89.2300° |
| Mean Bulk Density | 5.87 g/cm³ (14.5 km/s vesc) |
| Insolation Flux | 158.1880 S⊕ (~215,294 W/m²) |
| Habitable Zone Status | Exterior / Non-HZ |
| Celestial Distance | 1009.000 LY (309.353 pc) |