Kepler-239 c
Astrophysical Synthesis & Habitability Characterization
Kepler-239 c is a confirmed sub-neptune exoplanet orbiting the star Kepler-239, located approximately 2113.8 light-years (648.11 parsecs) from the Solar System. First announced in 2014 by Kepler using the Transit detection technique (producing an estimated primary transit depth of 0.091% across the stellar disk), this world measures 2.51 Earth radii and has a measured mass of 6.85 Earth masses. Combining its mass and radius yields a mean bulk density of 2.39 g/cm³ (an intermediate density indicative of a deep water-ice mantle or dense volatile envelope), a surface gravity of 1.09 g⊕ (10.69 m/s²), and an escape velocity of 18.5 km/s.
In its orbital architecture around Kepler-239, Kepler-239 c completes one full revolution every 56.228 Earth days at a semi-major axis of 0.268 AU (orbiting interior to Mercury's 0.387 AU benchmark in the Solar System). Its mean orbital velocity is approximately 51.9 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 366 K (+93°C / +199°F) and receiving 4.32 S⊕ (~5,873 W/m²), Kepler-239 c orbits interior to the runaway greenhouse boundary where surface liquid water cannot persist.
The host star Kepler-239 is classified as a stellar host with an effective photospheric temperature of 4,914 K, a radius of 0.763 R☉, a mass of 0.757 M☉, an estimated bolometric luminosity of 0.305 L☉. Stellar evolution modeling indicates an estimated stellar age of 3.31 Gyr and a metallicity of [Fe/H] = 0.17 dex (metal-rich relative to the Sun). From Earth, Kepler-239 shines at apparent V-band magnitude 15.252 (faint and requiring research-grade or CCD telescopic photometry) in the Northern celestial hemisphere. The Kepler-239 system is a multi-planet architecture hosting 2 confirmed worlds, with Kepler-239 c sharing its stellar neighborhood alongside Kepler-239 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-239 |
| Spectral Type | Unclassified |
| Effective Temp (Teff) | 4,914 K |
| Stellar Radius | 0.7630 R☉ |
| Stellar Mass | 0.7570 M☉ |
| Bolometric Luminosity | 0.305 L☉ |
| Metallicity [Fe/H] | 0.170 dex |
| Stellar Age | 3.310 Gyr |
| Apparent Magnitude | V: 15.252 · G: 15.233 |
| System Architecture | 1 Star, 2 Planets |
🪐 Orbital & Physical Dynamics
| Semi-Major Axis (a) | 0.268000 AU |
| Orbital Period | 56.228 days |
| Mean Orbital Velocity | 51.9 km/s |
| Orbital Eccentricity (e) | 0.00000 |
| Orbital Inclination (i) | 89.5600° |
| Mean Bulk Density | 2.39 g/cm³ (18.5 km/s vesc) |
| Insolation Flux | 4.3150 S⊕ (~5,873 W/m²) |
| Habitable Zone Status | Exterior / Non-HZ |
| Celestial Distance | 2113.800 LY (648.109 pc) |