K2-315 b
Astrophysical Synthesis & Habitability Characterization
K2-315 b is a confirmed terrestrial exoplanet orbiting the star K2-315, located approximately 185.8 light-years (56.97 parsecs) from the Solar System. First announced in 2020 by K2 using the Transit detection technique (producing an estimated primary transit depth of 0.1975% across the stellar disk), this world measures 0.95 Earth radii and has a measured mass of 0.809 Earth masses. Combining its mass and radius yields a mean bulk density of 5.2 g/cm³ (a terrestrial silicate-iron composition comparable to Earth (5.51 g/cm³)), a surface gravity of 0.9 g⊕ (8.83 m/s²), and an escape velocity of 10.3 km/s.
In its orbital architecture around K2-315, K2-315 b completes one full revolution every 3.144 Earth days.
⚠️ Thermal Regime (Irradiated / Hot Zone): At an equilibrium temperature of 460 K (+187°C / +369°F) and receiving 7.45 S⊕ (~10,139 W/m²), K2-315 b orbits interior to the runaway greenhouse boundary where surface liquid water cannot persist.
The host star K2-315 is classified as a low-mass red dwarf of spectral type M(3.5+/-0.5) V with an effective photospheric temperature of 3,300 K, a radius of 0.196 R☉, a mass of 0.174 M☉, an estimated bolometric luminosity of 0.00409 L☉. Stellar evolution modeling indicates an estimated stellar age of 1 Gyr and a metallicity of [Fe/H] = -0.24 dex (metal-poor relative to the Sun). From Earth, K2-315 shines at apparent V-band magnitude 17.67 (faint and requiring research-grade or CCD telescopic photometry) in the Southern celestial hemisphere.
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 | K2-315 |
| Spectral Type | M(3.5+/-0.5) V |
| Effective Temp (Teff) | 3,300 K |
| Stellar Radius | 0.1960 R☉ |
| Stellar Mass | 0.1740 M☉ |
| Bolometric Luminosity | 0.00409 L☉ |
| Metallicity [Fe/H] | -0.240 dex |
| Stellar Age | 1.000 Gyr |
| Apparent Magnitude | V: 17.670 · G: 15.679 |
| System Architecture | 1 Star, 1 Planet |
🪐 Orbital & Physical Dynamics
| Semi-Major Axis (a) | — |
| Orbital Period | 3.144 days |
| Orbital Eccentricity (e) | Circular (0.00) |
| Orbital Inclination (i) | 88.7400° |
| Mean Bulk Density | 5.2 g/cm³ (10.3 km/s vesc) |
| Insolation Flux | 7.4500 S⊕ (~10,139 W/m²) |
| Habitable Zone Status | Exterior / Non-HZ |
| Celestial Distance | 185.800 LY (56.969 pc) |