K2-152 b
Astrophysical Synthesis & Habitability Characterization
K2-152 b is a confirmed sub-neptune exoplanet orbiting the star K2-152, located approximately 353.7 light-years (108.45 parsecs) from the Solar System. First announced in 2018 by K2 using the Transit detection technique (producing an estimated primary transit depth of 0.1185% across the stellar disk), this world measures 2.29 Earth radii and has a measured mass of 5.86 Earth masses. Combining its mass and radius yields a mean bulk density of 2.69 g/cm³ (an intermediate density indicative of a deep water-ice mantle or dense volatile envelope), a surface gravity of 1.12 g⊕ (10.98 m/s²), and an escape velocity of 17.9 km/s.
In its orbital architecture around K2-152, K2-152 b completes one full revolution every 32.648 Earth days at a semi-major axis of 0.1716 AU (orbiting interior to Mercury's 0.387 AU benchmark in the Solar System). Its mean orbital velocity is approximately 57.2 km/s (compared to Earth's 29.8 km/s).
☁️ Atmospheric Regime (Volatile / Gas Envelope): With a radius of 2.290 R⊕, K2-152 b exceeds the empirical ~1.8–2.2 R⊕ Fulton radius valley threshold, indicating a substantial hydrogen-helium or supercritical volatile envelope without a conventional solid terrestrial surface.
The host star K2-152 is classified as a low-mass red dwarf of spectral type M0.0 V with an effective photospheric temperature of 4,044 K, a radius of 0.61 R☉, a mass of 0.63 M☉, an estimated bolometric luminosity of 0.089 L☉. Stellar evolution modeling indicates a metallicity of [Fe/H] = 0.12 dex (metal-rich relative to the Sun). From Earth, K2-152 shines at apparent V-band magnitude 13.728 (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 | K2-152 |
| Spectral Type | M0.0 V |
| Effective Temp (Teff) | 4,044 K |
| Stellar Radius | 0.6100 R☉ |
| Stellar Mass | 0.6300 M☉ |
| Bolometric Luminosity | 0.089 L☉ |
| Metallicity [Fe/H] | 0.120 dex |
| Stellar Age | — |
| Apparent Magnitude | V: 13.728 · G: 13.038 |
| System Architecture | 1 Star, 1 Planet |
🪐 Orbital & Physical Dynamics
| Semi-Major Axis (a) | 0.171600 AU |
| Orbital Period | 32.648 days |
| Mean Orbital Velocity | 57.2 km/s |
| Orbital Eccentricity (e) | Circular (0.00) |
| Orbital Inclination (i) | — |
| Mean Bulk Density | 2.69 g/cm³ (17.9 km/s vesc) |
| Insolation Flux | 2.9000 S⊕ (~3,947 W/m²) |
| Habitable Zone Status | Exterior / Non-HZ |
| Celestial Distance | 353.700 LY (108.449 pc) |