Kepler-237 c
Astrophysical Synthesis & Habitability Characterization
Kepler-237 c is a confirmed sub-neptune exoplanet orbiting the star Kepler-237, located approximately 2145.5 light-years (657.82 parsecs) from the Solar System. First announced in 2014 by Kepler using the Transit detection technique (producing an estimated primary transit depth of 0.0692% across the stellar disk), this world measures 2.08 Earth radii and has a measured mass of 4.98 Earth masses. Combining its mass and radius yields a mean bulk density of 3.05 g/cm³ (an intermediate density indicative of a deep water-ice mantle or dense volatile envelope), a surface gravity of 1.15 g⊕ (11.28 m/s²), and an escape velocity of 17.3 km/s.
In its orbital architecture around Kepler-237, Kepler-237 c completes one full revolution every 8.104 Earth days at a semi-major axis of 0.071 AU (orbiting interior to Mercury's 0.387 AU benchmark in the Solar System). Its mean orbital velocity is approximately 95.3 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 687 K (+414°C / +777°F) and receiving 60.64 S⊕ (~82,534 W/m²), Kepler-237 c orbits interior to the runaway greenhouse boundary where surface liquid water cannot persist.
The host star Kepler-237 is classified as a stellar host with an effective photospheric temperature of 4,861 K, a radius of 0.725 R☉, a mass of 0.696 M☉, an estimated bolometric luminosity of 0.263 L☉. Stellar evolution modeling indicates an estimated stellar age of 3.02 Gyr and a metallicity of [Fe/H] = 0.22 dex (metal-rich relative to the Sun). From Earth, Kepler-237 shines at apparent V-band magnitude 15.689 (faint and requiring research-grade or CCD telescopic photometry) in the Northern celestial hemisphere. The Kepler-237 system is a multi-planet architecture hosting 2 confirmed worlds, with Kepler-237 c sharing its stellar neighborhood alongside Kepler-237 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-237 |
| Spectral Type | Unclassified |
| Effective Temp (Teff) | 4,861 K |
| Stellar Radius | 0.7250 R☉ |
| Stellar Mass | 0.6960 M☉ |
| Bolometric Luminosity | 0.263 L☉ |
| Metallicity [Fe/H] | 0.220 dex |
| Stellar Age | 3.020 Gyr |
| Apparent Magnitude | V: 15.689 · G: 15.283 |
| System Architecture | 1 Star, 2 Planets |
🪐 Orbital & Physical Dynamics
| Semi-Major Axis (a) | 0.071000 AU |
| Orbital Period | 8.104 days |
| Mean Orbital Velocity | 95.3 km/s |
| Orbital Eccentricity (e) | 0.00000 |
| Orbital Inclination (i) | 89.8700° |
| Mean Bulk Density | 3.05 g/cm³ (17.3 km/s vesc) |
| Insolation Flux | 60.6420 S⊕ (~82,534 W/m²) |
| Habitable Zone Status | Exterior / Non-HZ |
| Celestial Distance | 2145.500 LY (657.822 pc) |