Kepler-201 c
Astrophysical Synthesis & Habitability Characterization
Kepler-201 c is a confirmed sub-neptune exoplanet orbiting the star Kepler-201, located approximately 2075.8 light-years (636.45 parsecs) from the Solar System. First announced in 2014 by Kepler using the Transit detection technique (producing an estimated primary transit depth of 0.0452% across the stellar disk), this world measures 2.85 Earth radii and has a measured mass of 8.5 Earth masses. Combining its mass and radius yields a mean bulk density of 2.02 g/cm³ (an intermediate density indicative of a deep water-ice mantle or dense volatile envelope), a surface gravity of 1.05 g⊕ (10.3 m/s²), and an escape velocity of 19.3 km/s.
In its orbital architecture around Kepler-201, Kepler-201 c completes one full revolution every 151.884 Earth days at a semi-major axis of 0.573 AU (situated at an orbital separation between Mercury's 0.39 AU and Venus's 0.72 AU). Its mean orbital velocity is approximately 41 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 378 K (+105°C / +221°F) and receiving 6.03 S⊕ (~8,211 W/m²), Kepler-201 c orbits interior to the runaway greenhouse boundary where surface liquid water cannot persist.
The host star Kepler-201 is classified as a stellar host with an effective photospheric temperature of 6,065 K, a radius of 1.229 R☉, a mass of 1.098 M☉, an estimated bolometric luminosity of 1.834 L☉. Stellar evolution modeling indicates an estimated stellar age of 4.07 Gyr and a metallicity of [Fe/H] = -0.044 dex (near-solar heavy-element abundance). From Earth, Kepler-201 shines at apparent V-band magnitude 12.991 (faint and requiring research-grade or CCD telescopic photometry) in the Northern celestial hemisphere. The Kepler-201 system is a multi-planet architecture hosting 2 confirmed worlds, with Kepler-201 c sharing its stellar neighborhood alongside Kepler-201 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-201 |
| Spectral Type | Unclassified |
| Effective Temp (Teff) | 6,065 K |
| Stellar Radius | 1.2290 R☉ |
| Stellar Mass | 1.0980 M☉ |
| Bolometric Luminosity | 1.834 L☉ |
| Metallicity [Fe/H] | -0.044 dex |
| Stellar Age | 4.070 Gyr |
| Apparent Magnitude | V: 12.991 · G: 12.920 |
| System Architecture | 1 Star, 2 Planets |
🪐 Orbital & Physical Dynamics
| Semi-Major Axis (a) | 0.573000 AU |
| Orbital Period | 151.884 days |
| Mean Orbital Velocity | 41 km/s |
| Orbital Eccentricity (e) | 0.00000 |
| Orbital Inclination (i) | 89.2700° |
| Mean Bulk Density | 2.02 g/cm³ (19.3 km/s vesc) |
| Insolation Flux | 6.0330 S⊕ (~8,211 W/m²) |
| Habitable Zone Status | Exterior / Non-HZ |
| Celestial Distance | 2075.800 LY (636.445 pc) |