Kepler-156 b
Astrophysical Synthesis & Habitability Characterization
Kepler-156 b is a confirmed sub-neptune exoplanet orbiting the star Kepler-156, located approximately 1446.4 light-years (443.48 parsecs) from the Solar System. First announced in 2014 by Kepler using the Transit detection technique (producing an estimated primary transit depth of 0.0683% across the stellar disk), this world measures 2.3 Earth radii and has a measured mass of 5.9 Earth masses. Combining its mass and radius yields a mean bulk density of 2.67 g/cm³ (an intermediate density indicative of a deep water-ice mantle or dense volatile envelope), a surface gravity of 1.12 g⊕ (10.98 m/s²), and an escape velocity of 17.9 km/s.
In its orbital architecture around Kepler-156, Kepler-156 b completes one full revolution every 4.973 Earth days at a semi-major axis of 0.054 AU (orbiting interior to Mercury's 0.387 AU benchmark in the Solar System). Its mean orbital velocity is approximately 118.1 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.
⚠️ Thermal Regime (Irradiated / Hot Zone): At an equilibrium temperature of 867 K (+594°C / +1101°F) and receiving 135.08 S⊕ (~183,840 W/m²), Kepler-156 b orbits interior to the runaway greenhouse boundary where surface liquid water cannot persist.
The host star Kepler-156 is classified as a stellar host with an effective photospheric temperature of 5,094 K, a radius of 0.807 R☉, a mass of 0.864 M☉, an estimated bolometric luminosity of 0.393 L☉. Stellar evolution modeling indicates an estimated stellar age of 3.39 Gyr and a metallicity of [Fe/H] = 0.254 dex (metal-rich relative to the Sun). From Earth, Kepler-156 shines at apparent V-band magnitude 14.339 (faint and requiring research-grade or CCD telescopic photometry) in the Northern celestial hemisphere. The Kepler-156 system is a multi-planet architecture hosting 2 confirmed worlds, with Kepler-156 b sharing its stellar neighborhood alongside Kepler-156 c.
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-156 |
| Spectral Type | Unclassified |
| Effective Temp (Teff) | 5,094 K |
| Stellar Radius | 0.8070 R☉ |
| Stellar Mass | 0.8640 M☉ |
| Bolometric Luminosity | 0.393 L☉ |
| Metallicity [Fe/H] | 0.254 dex |
| Stellar Age | 3.390 Gyr |
| Apparent Magnitude | V: 14.339 · G: 14.156 |
| System Architecture | 1 Star, 2 Planets |
🪐 Orbital & Physical Dynamics
| Semi-Major Axis (a) | 0.054000 AU |
| Orbital Period | 4.973 days |
| Mean Orbital Velocity | 118.1 km/s |
| Orbital Eccentricity (e) | 0.00000 |
| Orbital Inclination (i) | 86.7500° |
| Mean Bulk Density | 2.67 g/cm³ (17.9 km/s vesc) |
| Insolation Flux | 135.0770 S⊕ (~183,840 W/m²) |
| Habitable Zone Status | Exterior / Non-HZ |
| Celestial Distance | 1446.400 LY (443.483 pc) |