Kepler-157 c
Astrophysical Synthesis & Habitability Characterization
Kepler-157 c is a confirmed sub-neptune exoplanet orbiting the star Kepler-157, located approximately 2523.5 light-years (773.71 parsecs) from the Solar System. First announced in 2014 by Kepler using the Transit detection technique (producing an estimated primary transit depth of 0.0387% across the stellar disk), this world measures 2.24 Earth radii and has a measured mass of 5.65 Earth masses. Combining its mass and radius yields a mean bulk density of 2.77 g/cm³ (an intermediate density indicative of a deep water-ice mantle or dense volatile envelope), a surface gravity of 1.13 g⊕ (11.08 m/s²), and an escape velocity of 17.8 km/s.
In its orbital architecture around Kepler-157, Kepler-157 c completes one full revolution every 13.541 Earth days at a semi-major axis of 0.11 AU (orbiting interior to Mercury's 0.387 AU benchmark in the Solar System). Its mean orbital velocity is approximately 88.4 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 779 K (+506°C / +943°F) and receiving 101.75 S⊕ (~138,487 W/m²), Kepler-157 c orbits interior to the runaway greenhouse boundary where surface liquid water cannot persist.
The host star Kepler-157 is classified as a stellar host with an effective photospheric temperature of 5,774 K, a radius of 1.044 R☉, a mass of 0.95 M☉, an estimated bolometric luminosity of 1.087 L☉. Stellar evolution modeling indicates an estimated stellar age of 7.59 Gyr and a metallicity of [Fe/H] = -0.059 dex (near-solar heavy-element abundance). From Earth, Kepler-157 shines at apparent V-band magnitude 14.206 (faint and requiring research-grade or CCD telescopic photometry) in the Northern celestial hemisphere. The Kepler-157 system is a multi-planet architecture hosting 3 confirmed worlds, with Kepler-157 c sharing its stellar neighborhood alongside Kepler-157 b, Kepler-157 d.
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-157 |
| Spectral Type | Unclassified |
| Effective Temp (Teff) | 5,774 K |
| Stellar Radius | 1.0440 R☉ |
| Stellar Mass | 0.9500 M☉ |
| Bolometric Luminosity | 1.087 L☉ |
| Metallicity [Fe/H] | -0.059 dex |
| Stellar Age | 7.590 Gyr |
| Apparent Magnitude | V: 14.206 · G: 14.037 |
| System Architecture | 1 Star, 3 Planets |
🪐 Orbital & Physical Dynamics
| Semi-Major Axis (a) | 0.110000 AU |
| Orbital Period | 13.541 days |
| Mean Orbital Velocity | 88.4 km/s |
| Orbital Eccentricity (e) | 0.00000 |
| Orbital Inclination (i) | 89.5600° |
| Mean Bulk Density | 2.77 g/cm³ (17.8 km/s vesc) |
| Insolation Flux | 101.7540 S⊕ (~138,487 W/m²) |
| Habitable Zone Status | Exterior / Non-HZ |
| Celestial Distance | 2523.500 LY (773.713 pc) |