Kepler-158 b
Astrophysical Synthesis & Habitability Characterization
Kepler-158 b is a confirmed sub-neptune exoplanet orbiting the star Kepler-158, located approximately 1028 light-years (315.18 parsecs) from the Solar System. First announced in 2014 by Kepler using the Transit detection technique (producing an estimated primary transit depth of 0.097% across the stellar disk), this world measures 2.12 Earth radii and has a measured mass of 5.14 Earth masses. Combining its mass and radius yields a mean bulk density of 2.97 g/cm³ (an intermediate density indicative of a deep water-ice mantle or dense volatile envelope), a surface gravity of 1.14 g⊕ (11.18 m/s²), and an escape velocity of 17.4 km/s.
In its orbital architecture around Kepler-158, Kepler-158 b completes one full revolution every 16.709 Earth days at a semi-major axis of 0.111 AU (orbiting interior to Mercury's 0.387 AU benchmark in the Solar System). Its mean orbital velocity is approximately 72.3 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 500 K (+227°C / +441°F) and receiving 13.63 S⊕ (~18,556 W/m²), Kepler-158 b orbits interior to the runaway greenhouse boundary where surface liquid water cannot persist.
The host star Kepler-158 is classified as an orange K-type star of spectral type K with an effective photospheric temperature of 4,623 K, a radius of 0.624 R☉, a mass of 0.655 M☉, an estimated bolometric luminosity of 0.16 L☉. Stellar evolution modeling indicates an estimated stellar age of 13.9 Gyr and a metallicity of [Fe/H] = -0.3 dex (metal-poor relative to the Sun). From Earth, Kepler-158 shines at apparent V-band magnitude 14.743 (faint and requiring research-grade or CCD telescopic photometry) in the Northern celestial hemisphere. The Kepler-158 system is a multi-planet architecture hosting 3 confirmed worlds, with Kepler-158 b sharing its stellar neighborhood alongside Kepler-158 d, Kepler-158 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-158 |
| Spectral Type | K |
| Effective Temp (Teff) | 4,623 K |
| Stellar Radius | 0.6240 R☉ |
| Stellar Mass | 0.6550 M☉ |
| Bolometric Luminosity | 0.16 L☉ |
| Metallicity [Fe/H] | -0.300 dex |
| Stellar Age | 13.900 Gyr |
| Apparent Magnitude | V: 14.743 · G: 14.417 |
| System Architecture | 1 Star, 3 Planets |
🪐 Orbital & Physical Dynamics
| Semi-Major Axis (a) | 0.111000 AU |
| Orbital Period | 16.709 days |
| Mean Orbital Velocity | 72.3 km/s |
| Orbital Eccentricity (e) | 0.00000 |
| Orbital Inclination (i) | 88.2000° |
| Mean Bulk Density | 2.97 g/cm³ (17.4 km/s vesc) |
| Insolation Flux | 13.6340 S⊕ (~18,556 W/m²) |
| Habitable Zone Status | Exterior / Non-HZ |
| Celestial Distance | 1028.000 LY (315.177 pc) |