K2-195 b
Astrophysical Synthesis & Habitability Characterization
K2-195 b is a confirmed sub-neptune exoplanet orbiting the star K2-195, located approximately 1027.4 light-years (315.01 parsecs) from the Solar System. First announced in 2018 by K2 using the Transit detection technique (producing an estimated primary transit depth of 0.084% across the stellar disk), this world measures 3.13 Earth radii (0.28 Jupiter radii) and has a measured mass of 9.96 Earth masses. Combining its mass and radius yields a mean bulk density of 1.79 g/cm³ (a low bulk density dominated by an extended hydrogen-helium gaseous envelope), a surface gravity of 1.02 g⊕ (10 m/s²), and an escape velocity of 20 km/s.
In its orbital architecture around K2-195, K2-195 b completes one full revolution every 15.853 Earth days at a semi-major axis of 0.1208 AU (orbiting interior to Mercury's 0.387 AU benchmark in the Solar System). Its mean orbital velocity is approximately 82.9 km/s (compared to Earth's 29.8 km/s).
⚠️ Thermal Regime (Irradiated / Hot Zone): At an equilibrium temperature of 720 K (+447°C / +837°F) and receiving 66.67 S⊕ (~90,733 W/m²), K2-195 b orbits interior to the runaway greenhouse boundary where surface liquid water cannot persist.
The host star K2-195 is classified as a stellar host with an effective photospheric temperature of 5,713 K, a radius of 0.99 R☉, a mass of 0.94 M☉, an estimated bolometric luminosity of 0.937 L☉. Stellar evolution modeling indicates a metallicity of [Fe/H] = -0.1 dex (near-solar heavy-element abundance). From Earth, K2-195 shines at apparent V-band magnitude 12.524 (faint and requiring research-grade or CCD telescopic photometry) in the Southern celestial hemisphere. The K2-195 system is a multi-planet architecture hosting 2 confirmed worlds, with K2-195 b sharing its stellar neighborhood alongside K2-195 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: K2 · Catalogue Source: NASA Exoplanet Archive (IPAC / Caltech).
☀️ Host Star Telemetry
| Host Star Name | K2-195 |
| Spectral Type | Unclassified |
| Effective Temp (Teff) | 5,713 K |
| Stellar Radius | 0.9900 R☉ |
| Stellar Mass | 0.9400 M☉ |
| Bolometric Luminosity | 0.937 L☉ |
| Metallicity [Fe/H] | -0.100 dex |
| Stellar Age | — |
| Apparent Magnitude | V: 12.524 · G: 12.324 |
| System Architecture | 1 Star, 2 Planets |
🪐 Orbital & Physical Dynamics
| Semi-Major Axis (a) | 0.120800 AU |
| Orbital Period | 15.853 days |
| Mean Orbital Velocity | 82.9 km/s |
| Orbital Eccentricity (e) | Circular (0.00) |
| Orbital Inclination (i) | 89.0407° |
| Mean Bulk Density | 1.79 g/cm³ (20 km/s vesc) |
| Insolation Flux | 66.6667 S⊕ (~90,733 W/m²) |
| Habitable Zone Status | Exterior / Non-HZ |
| Celestial Distance | 1027.400 LY (315.014 pc) |