Kepler-213 c
Astrophysical Synthesis & Habitability Characterization
Kepler-213 c is a confirmed sub-neptune exoplanet orbiting the star Kepler-213, located approximately 2070.9 light-years (634.94 parsecs) from the Solar System. First announced in 2014 by Kepler using the Transit detection technique (producing an estimated primary transit depth of 0.0322% across the stellar disk), this world measures 2.34 Earth radii and has a measured mass of 6.08 Earth masses. Combining its mass and radius yields a mean bulk density of 2.62 g/cm³ (an intermediate density indicative of a deep water-ice mantle or dense volatile envelope), a surface gravity of 1.11 g⊕ (10.89 m/s²), and an escape velocity of 18 km/s.
In its orbital architecture around Kepler-213, Kepler-213 c completes one full revolution every 4.823 Earth days at a semi-major axis of 0.057 AU (orbiting interior to Mercury's 0.387 AU benchmark in the Solar System). Its mean orbital velocity is approximately 128.6 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 1060 K (+787°C / +1449°F) and receiving 339.54 S⊕ (~462,108 W/m²), Kepler-213 c orbits interior to the runaway greenhouse boundary where surface liquid water cannot persist.
The host star Kepler-213 is classified as a stellar host with an effective photospheric temperature of 5,696 K, a radius of 1.195 R☉, a mass of 1.07 M☉, an estimated bolometric luminosity of 1.349 L☉. Stellar evolution modeling indicates an estimated stellar age of 1.62 Gyr and a metallicity of [Fe/H] = 0.15 dex (metal-rich relative to the Sun). From Earth, Kepler-213 shines at apparent V-band magnitude 13.705 (faint and requiring research-grade or CCD telescopic photometry) in the Northern celestial hemisphere. The Kepler-213 system is a multi-planet architecture hosting 2 confirmed worlds, with Kepler-213 c sharing its stellar neighborhood alongside Kepler-213 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-213 |
| Spectral Type | Unclassified |
| Effective Temp (Teff) | 5,696 K |
| Stellar Radius | 1.1950 R☉ |
| Stellar Mass | 1.0700 M☉ |
| Bolometric Luminosity | 1.349 L☉ |
| Metallicity [Fe/H] | 0.150 dex |
| Stellar Age | 1.620 Gyr |
| Apparent Magnitude | V: 13.705 · G: 13.602 |
| System Architecture | 1 Star, 2 Planets |
🪐 Orbital & Physical Dynamics
| Semi-Major Axis (a) | 0.057000 AU |
| Orbital Period | 4.823 days |
| Mean Orbital Velocity | 128.6 km/s |
| Orbital Eccentricity (e) | 0.00000 |
| Orbital Inclination (i) | 87.5600° |
| Mean Bulk Density | 2.62 g/cm³ (18 km/s vesc) |
| Insolation Flux | 339.5360 S⊕ (~462,108 W/m²) |
| Habitable Zone Status | Exterior / Non-HZ |
| Celestial Distance | 2070.900 LY (634.939 pc) |