Kepler-252 c
Astrophysical Synthesis & Habitability Characterization
Kepler-252 c is a confirmed sub-neptune exoplanet orbiting the star Kepler-252, located approximately 1237.5 light-years (379.42 parsecs) from the Solar System. First announced in 2014 by Kepler using the Transit detection technique (producing an estimated primary transit depth of 0.1289% across the stellar disk), this world measures 2.15 Earth radii and has a measured mass of 5.27 Earth masses. Combining its mass and radius yields a mean bulk density of 2.92 g/cm³ (an intermediate density indicative of a deep water-ice mantle or dense volatile envelope), a surface gravity of 1.14 g⊕ (11.18 m/s²), and an escape velocity of 17.5 km/s.
In its orbital architecture around Kepler-252, Kepler-252 c completes one full revolution every 10.848 Earth days at a semi-major axis of 0.08 AU (orbiting interior to Mercury's 0.387 AU benchmark in the Solar System). Its mean orbital velocity is approximately 80.2 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 499 K (+226°C / +439°F) and receiving 20.51 S⊕ (~27,910 W/m²), Kepler-252 c orbits interior to the runaway greenhouse boundary where surface liquid water cannot persist.
The host star Kepler-252 is classified as a low-mass red dwarf of spectral type M0 V with an effective photospheric temperature of 4,208 K, a radius of 0.549 R☉, a mass of 0.61 M☉, an estimated bolometric luminosity of 0.085 L☉. Stellar evolution modeling indicates an estimated stellar age of 13.9 Gyr and a metallicity of [Fe/H] = -0.13 dex (metal-poor relative to the Sun). From Earth, Kepler-252 shines at apparent V-band magnitude 15.406 (faint and requiring research-grade or CCD telescopic photometry) in the Northern celestial hemisphere. The Kepler-252 system is a multi-planet architecture hosting 2 confirmed worlds, with Kepler-252 c sharing its stellar neighborhood alongside Kepler-252 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-252 |
| Spectral Type | M0 V |
| Effective Temp (Teff) | 4,208 K |
| Stellar Radius | 0.5490 R☉ |
| Stellar Mass | 0.6100 M☉ |
| Bolometric Luminosity | 0.085 L☉ |
| Metallicity [Fe/H] | -0.130 dex |
| Stellar Age | 13.900 Gyr |
| Apparent Magnitude | V: 15.406 · G: 15.029 |
| System Architecture | 1 Star, 2 Planets |
🪐 Orbital & Physical Dynamics
| Semi-Major Axis (a) | 0.080000 AU |
| Orbital Period | 10.848 days |
| Mean Orbital Velocity | 80.2 km/s |
| Orbital Eccentricity (e) | 0.00000 |
| Orbital Inclination (i) | 89.5700° |
| Mean Bulk Density | 2.92 g/cm³ (17.5 km/s vesc) |
| Insolation Flux | 20.5070 S⊕ (~27,910 W/m²) |
| Habitable Zone Status | Exterior / Non-HZ |
| Celestial Distance | 1237.500 LY (379.424 pc) |