Kepler-255 c
Astrophysical Synthesis & Habitability Characterization
Kepler-255 c is a confirmed sub-neptune exoplanet orbiting the star Kepler-255, located approximately 3432.9 light-years (1052.53 parsecs) from the Solar System. First announced in 2014 by Kepler using the Transit detection technique (producing an estimated primary transit depth of 0.0863% across the stellar disk), this world measures 2.99 Earth radii and has a measured mass of 9.22 Earth masses. Combining its mass and radius yields a mean bulk density of 1.9 g/cm³ (a low bulk density dominated by an extended hydrogen-helium gaseous envelope), a surface gravity of 1.03 g⊕ (10.1 m/s²), and an escape velocity of 19.6 km/s.
In its orbital architecture around Kepler-255, Kepler-255 c completes one full revolution every 9.946 Earth days at a semi-major axis of 0.092 AU (orbiting interior to Mercury's 0.387 AU benchmark in the Solar System). Its mean orbital velocity is approximately 100.6 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 807 K (+534°C / +993°F) and receiving 83.26 S⊕ (~113,322 W/m²), Kepler-255 c orbits interior to the runaway greenhouse boundary where surface liquid water cannot persist.
The host star Kepler-255 is classified as a stellar host with an effective photospheric temperature of 5,573 K, a radius of 0.933 R☉, a mass of 0.867 M☉, an estimated bolometric luminosity of 0.753 L☉. Stellar evolution modeling indicates an estimated stellar age of 2.4 Gyr and a metallicity of [Fe/H] = 0.339 dex (metal-rich relative to the Sun). From Earth, Kepler-255 shines at apparent V-band magnitude 15.699 (faint and requiring research-grade or CCD telescopic photometry) in the Northern celestial hemisphere. The Kepler-255 system is a multi-planet architecture hosting 3 confirmed worlds, with Kepler-255 c sharing its stellar neighborhood alongside Kepler-255 d, Kepler-255 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-255 |
| Spectral Type | Unclassified |
| Effective Temp (Teff) | 5,573 K |
| Stellar Radius | 0.9330 R☉ |
| Stellar Mass | 0.8670 M☉ |
| Bolometric Luminosity | 0.753 L☉ |
| Metallicity [Fe/H] | 0.339 dex |
| Stellar Age | 2.400 Gyr |
| Apparent Magnitude | V: 15.699 · G: 15.528 |
| System Architecture | 1 Star, 3 Planets |
🪐 Orbital & Physical Dynamics
| Semi-Major Axis (a) | 0.092000 AU |
| Orbital Period | 9.946 days |
| Mean Orbital Velocity | 100.6 km/s |
| Orbital Eccentricity (e) | 0.00000 |
| Orbital Inclination (i) | 89.9100° |
| Mean Bulk Density | 1.9 g/cm³ (19.6 km/s vesc) |
| Insolation Flux | 83.2640 S⊕ (~113,322 W/m²) |
| Habitable Zone Status | Exterior / Non-HZ |
| Celestial Distance | 3432.900 LY (1052.530 pc) |