K2-32 c
Astrophysical Synthesis & Habitability Characterization
K2-32 c is a confirmed sub-neptune exoplanet orbiting the star K2-32, located approximately 514.3 light-years (157.68 parsecs) from the Solar System. First announced in 2016 by K2 using the Transit detection technique (producing an estimated primary transit depth of 0.1116% across the stellar disk), this world measures 3.134 Earth radii (0.28 Jupiter radii) and has a measured mass of 8.1 Earth masses. Combining its mass and radius yields a mean bulk density of 1.45 g/cm³ (a low bulk density dominated by an extended hydrogen-helium gaseous envelope), a surface gravity of 0.82 g⊕ (8.04 m/s²), and an escape velocity of 18 km/s.
In its orbital architecture around K2-32, K2-32 c completes one full revolution every 20.661 Earth days at a semi-major axis of 0.13843 AU (orbiting interior to Mercury's 0.387 AU benchmark in the Solar System). Its mean orbital velocity is approximately 72.9 km/s (compared to Earth's 29.8 km/s). With a near-circular eccentricity of e = 0.049 (ranging from 0.1316 AU at periapsis to 0.1452 AU at apoapsis), the planet experiences minimal orbital distance variation.
⚠️ Thermal Regime (Irradiated / Hot Zone): At an equilibrium temperature of 634 K (+361°C / +682°F) and receiving 26.20 S⊕ (~35,658 W/m²), K2-32 c orbits interior to the runaway greenhouse boundary where surface liquid water cannot persist.
The host star K2-32 is classified as a solar-type yellow star of spectral type G9 V with an effective photospheric temperature of 5,271 K, a radius of 0.86 R☉, a mass of 0.83 M☉, an estimated bolometric luminosity of 0.512 L☉. Stellar evolution modeling indicates an estimated stellar age of 7.9 Gyr and a metallicity of [Fe/H] = -0.06 dex (near-solar heavy-element abundance). From Earth, K2-32 shines at apparent V-band magnitude 12.304 (faint and requiring research-grade or CCD telescopic photometry) in the Southern celestial hemisphere. The K2-32 system is a multi-planet architecture hosting 4 confirmed worlds, with K2-32 c sharing its stellar neighborhood alongside K2-32 e, K2-32 b, K2-32 d.
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 | K2-32 |
| Spectral Type | G9 V |
| Effective Temp (Teff) | 5,271 K |
| Stellar Radius | 0.8600 R☉ |
| Stellar Mass | 0.8300 M☉ |
| Bolometric Luminosity | 0.512 L☉ |
| Metallicity [Fe/H] | -0.060 dex |
| Stellar Age | 7.900 Gyr |
| Apparent Magnitude | V: 12.304 · G: 12.004 |
| System Architecture | 2 Stars, 4 Planets |
🪐 Orbital & Physical Dynamics
| Semi-Major Axis (a) | 0.138430 AU |
| Orbital Period | 20.661 days |
| Mean Orbital Velocity | 72.9 km/s |
| Orbital Eccentricity (e) | 0.04900 |
| Orbital Inclination (i) | 89.4000° |
| Mean Bulk Density | 1.45 g/cm³ (18 km/s vesc) |
| Insolation Flux | 26.2000 S⊕ (~35,658 W/m²) |
| Habitable Zone Status | Exterior / Non-HZ |
| Celestial Distance | 514.300 LY (157.682 pc) |