Kepler-406 c
Astrophysical Synthesis & Habitability Characterization
Kepler-406 c is a confirmed terrestrial exoplanet orbiting the star Kepler-406, located approximately 1187.3 light-years (364.03 parsecs) from the Solar System. First announced in 2014 by Kepler using the Transit detection technique (producing an estimated primary transit depth of 0.0053% across the stellar disk), this world measures 0.85 Earth radii and has a measured mass of 2.71 Earth masses. Combining its mass and radius yields a mean bulk density of 24.33 g/cm³ (an iron-enriched, high-compression rocky core), a surface gravity of 3.75 g⊕ (36.77 m/s²), and an escape velocity of 20 km/s.
In its orbital architecture around Kepler-406, Kepler-406 c completes one full revolution every 4.623 Earth days at a semi-major axis of 0.05531 AU (orbiting interior to Mercury's 0.387 AU benchmark in the Solar System). Its mean orbital velocity is approximately 130.1 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 1050 K (+777°C / +1431°F) and receiving 349.77 S⊕ (~476,036 W/m²), Kepler-406 c orbits interior to the runaway greenhouse boundary where surface liquid water cannot persist.
The host star Kepler-406 is classified as a stellar host with an effective photospheric temperature of 5,538 K, a radius of 1.07 R☉, a mass of 1.07 M☉, an estimated bolometric luminosity of 0.966 L☉. Stellar evolution modeling indicates an estimated stellar age of 5.84 Gyr and a metallicity of [Fe/H] = 0.18 dex (metal-rich relative to the Sun). From Earth, Kepler-406 shines at apparent V-band magnitude 12.603 (faint and requiring research-grade or CCD telescopic photometry) in the Northern celestial hemisphere. The Kepler-406 system is a multi-planet architecture hosting 2 confirmed worlds, with Kepler-406 c sharing its stellar neighborhood alongside Kepler-406 b.
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-406 |
| Spectral Type | Unclassified |
| Effective Temp (Teff) | 5,538 K |
| Stellar Radius | 1.0700 R☉ |
| Stellar Mass | 1.0700 M☉ |
| Bolometric Luminosity | 0.966 L☉ |
| Metallicity [Fe/H] | 0.180 dex |
| Stellar Age | 5.840 Gyr |
| Apparent Magnitude | V: 12.603 · G: 12.490 |
| System Architecture | 1 Star, 2 Planets |
🪐 Orbital & Physical Dynamics
| Semi-Major Axis (a) | 0.055310 AU |
| Orbital Period | 4.623 days |
| Mean Orbital Velocity | 130.1 km/s |
| Orbital Eccentricity (e) | 0.00000 |
| Orbital Inclination (i) | 87.9600° |
| Mean Bulk Density | 24.33 g/cm³ (20 km/s vesc) |
| Insolation Flux | 349.7690 S⊕ (~476,036 W/m²) |
| Habitable Zone Status | Exterior / Non-HZ |
| Celestial Distance | 1187.300 LY (364.030 pc) |