Kepler-136 b
Astrophysical Synthesis & Habitability Characterization
Kepler-136 b is a confirmed sub-neptune exoplanet orbiting the star Kepler-136, located approximately 1372.5 light-years (420.82 parsecs) from the Solar System. First announced in 2014 by Kepler using the Transit detection technique (producing an estimated primary transit depth of 0.0192% across the stellar disk), this world measures 2.05 Earth radii and has a measured mass of 19.8 Earth masses. Combining its mass and radius yields a mean bulk density of 12.67 g/cm³ (an iron-enriched, high-compression rocky core), a surface gravity of 4.71 g⊕ (46.19 m/s²), and an escape velocity of 34.8 km/s.
In its orbital architecture around Kepler-136, Kepler-136 b completes one full revolution every 11.579 Earth days at a semi-major axis of 0.106 AU (orbiting interior to Mercury's 0.387 AU benchmark in the Solar System). Its mean orbital velocity is approximately 99.6 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 951 K (+678°C / +1252°F) and receiving 257.98 S⊕ (~351,116 W/m²), Kepler-136 b orbits interior to the runaway greenhouse boundary where surface liquid water cannot persist.
The host star Kepler-136 is classified as a stellar host with an effective photospheric temperature of 6,165 K, a radius of 1.355 R☉, a mass of 1.204 M☉, an estimated bolometric luminosity of 2.38 L☉. Stellar evolution modeling indicates an estimated stellar age of 2.75 Gyr and a metallicity of [Fe/H] = 0 dex (near-solar heavy-element abundance). From Earth, Kepler-136 shines at apparent V-band magnitude 11.822 (faint and requiring research-grade or CCD telescopic photometry) in the Northern celestial hemisphere. The Kepler-136 system is a multi-planet architecture hosting 2 confirmed worlds, with Kepler-136 b sharing its stellar neighborhood alongside Kepler-136 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-136 |
| Spectral Type | Unclassified |
| Effective Temp (Teff) | 6,165 K |
| Stellar Radius | 1.3550 R☉ |
| Stellar Mass | 1.2040 M☉ |
| Bolometric Luminosity | 2.38 L☉ |
| Metallicity [Fe/H] | 0.000 dex |
| Stellar Age | 2.750 Gyr |
| Apparent Magnitude | V: 11.822 · G: 11.754 |
| System Architecture | 2 Stars, 2 Planets |
🪐 Orbital & Physical Dynamics
| Semi-Major Axis (a) | 0.106000 AU |
| Orbital Period | 11.579 days |
| Mean Orbital Velocity | 99.6 km/s |
| Orbital Eccentricity (e) | 0.00000 |
| Orbital Inclination (i) | 89.3300° |
| Mean Bulk Density | 12.67 g/cm³ (34.8 km/s vesc) |
| Insolation Flux | 257.9840 S⊕ (~351,116 W/m²) |
| Habitable Zone Status | Exterior / Non-HZ |
| Celestial Distance | 1372.500 LY (420.818 pc) |