K2-158 c
Astrophysical Synthesis & Habitability Characterization
K2-158 c is a confirmed super-earth exoplanet orbiting the star K2-158, located approximately 643.5 light-years (197.3 parsecs) from the Solar System. First announced in 2018 by K2 using the Transit detection technique (producing an estimated primary transit depth of 0.0153% across the stellar disk), this world measures 1.28 Earth radii and has a measured mass of 2.18 Earth masses. Combining its mass and radius yields a mean bulk density of 5.73 g/cm³ (a terrestrial silicate-iron composition comparable to Earth (5.51 g/cm³)), a surface gravity of 1.33 g⊕ (13.04 m/s²), and an escape velocity of 14.6 km/s.
In its orbital architecture around K2-158, K2-158 c completes one full revolution every 5.903 Earth days at a semi-major axis of 0.0622 AU (orbiting interior to Mercury's 0.387 AU benchmark in the Solar System). Its mean orbital velocity is approximately 114.6 km/s (compared to Earth's 29.8 km/s).
⚠️ Thermal Regime (Irradiated / Hot Zone): At an equilibrium temperature of 948 K (+675°C / +1247°F) and receiving 177.60 S⊕ (~241,714 W/m²), K2-158 c orbits interior to the runaway greenhouse boundary where surface liquid water cannot persist.
The host star K2-158 is classified as a stellar host with an effective photospheric temperature of 5,503 K, a radius of 0.95 R☉, a mass of 0.92 M☉, an estimated bolometric luminosity of 0.743 L☉. Stellar evolution modeling indicates a metallicity of [Fe/H] = 0.07 dex (metal-rich relative to the Sun). From Earth, K2-158 shines at apparent V-band magnitude 11.774 (faint and requiring research-grade or CCD telescopic photometry) in the Southern celestial hemisphere. The K2-158 system is a multi-planet architecture hosting 2 confirmed worlds, with K2-158 c sharing its stellar neighborhood alongside K2-158 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: K2 · Catalogue Source: NASA Exoplanet Archive (IPAC / Caltech).
☀️ Host Star Telemetry
| Host Star Name | K2-158 |
| Spectral Type | Unclassified |
| Effective Temp (Teff) | 5,503 K |
| Stellar Radius | 0.9500 R☉ |
| Stellar Mass | 0.9200 M☉ |
| Bolometric Luminosity | 0.743 L☉ |
| Metallicity [Fe/H] | 0.070 dex |
| Stellar Age | — |
| Apparent Magnitude | V: 11.774 · G: 11.613 |
| System Architecture | 1 Star, 2 Planets |
🪐 Orbital & Physical Dynamics
| Semi-Major Axis (a) | 0.062200 AU |
| Orbital Period | 5.903 days |
| Mean Orbital Velocity | 114.6 km/s |
| Orbital Eccentricity (e) | Circular (0.00) |
| Orbital Inclination (i) | — |
| Mean Bulk Density | 5.73 g/cm³ (14.6 km/s vesc) |
| Insolation Flux | 177.6001 S⊕ (~241,714 W/m²) |
| Habitable Zone Status | Exterior / Non-HZ |
| Celestial Distance | 643.500 LY (197.299 pc) |