Kepler-55 c
Astrophysical Synthesis & Habitability Characterization
Kepler-55 c is a confirmed sub-neptune exoplanet orbiting the star Kepler-55, located approximately 1887.8 light-years (578.8 parsecs) from the Solar System. First announced in 2012 by Kepler using the Transit detection technique (producing an estimated primary transit depth of 0.122% across the stellar disk), this world measures 2.21 Earth radii and has a measured mass of 69.8 Earth masses (0.22 Jupiter masses). Combining its mass and radius yields a mean bulk density of 35.66 g/cm³ (an iron-enriched, high-compression rocky core), a surface gravity of 14.29 g⊕ (140.14 m/s²), and an escape velocity of 62.9 km/s.
In its orbital architecture around Kepler-55, Kepler-55 c completes one full revolution every 42.152 Earth days at a semi-major axis of 0.2095 AU (orbiting interior to Mercury's 0.387 AU benchmark in the Solar System). Its mean orbital velocity is approximately 54.1 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.
☁️ Atmospheric Regime (Volatile / Gas Envelope): With a radius of 2.210 R⊕, Kepler-55 c exceeds the empirical ~1.8–2.2 R⊕ Fulton radius valley threshold, indicating a substantial hydrogen-helium or supercritical volatile envelope without a conventional solid terrestrial surface.
The host star Kepler-55 is classified as a stellar host with an effective photospheric temperature of 4,362 K, a radius of 0.58 R☉, a mass of 0.62 M☉, an estimated bolometric luminosity of 0.109 L☉. Stellar evolution modeling indicates an estimated stellar age of 2.34 Gyr and a metallicity of [Fe/H] = -0.01 dex (near-solar heavy-element abundance). From Earth, Kepler-55 shines at apparent V-band magnitude 15.746 (faint and requiring research-grade or CCD telescopic photometry) in the Northern celestial hemisphere. The Kepler-55 system is a multi-planet architecture hosting 5 confirmed worlds, with Kepler-55 c sharing its stellar neighborhood alongside Kepler-55 d, Kepler-55 e, Kepler-55 f, Kepler-55 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-55 |
| Spectral Type | Unclassified |
| Effective Temp (Teff) | 4,362 K |
| Stellar Radius | 0.5800 R☉ |
| Stellar Mass | 0.6200 M☉ |
| Bolometric Luminosity | 0.109 L☉ |
| Metallicity [Fe/H] | -0.010 dex |
| Stellar Age | 2.340 Gyr |
| Apparent Magnitude | V: 15.746 · G: 15.781 |
| System Architecture | 1 Star, 5 Planets |
🪐 Orbital & Physical Dynamics
| Semi-Major Axis (a) | 0.209500 AU |
| Orbital Period | 42.152 days |
| Mean Orbital Velocity | 54.1 km/s |
| Orbital Eccentricity (e) | 0.00000 |
| Orbital Inclination (i) | 89.9600° |
| Mean Bulk Density | 35.66 g/cm³ (62.9 km/s vesc) |
| Insolation Flux | 3.8400 S⊕ (~5,226 W/m²) |
| Habitable Zone Status | Exterior / Non-HZ |
| Celestial Distance | 1887.800 LY (578.796 pc) |