Kepler-32 d
Astrophysical Synthesis & Habitability Characterization
Kepler-32 d is a confirmed sub-neptune exoplanet orbiting the star Kepler-32, located approximately 1056.2 light-years (323.85 parsecs) from the Solar System. First announced in 2012 by Kepler using the Transit detection technique (producing an estimated primary transit depth of 0.2181% across the stellar disk), this world measures 2.7 Earth radii and has a measured mass of 39.909 Earth masses (0.13 Jupiter masses). Combining its mass and radius yields a mean bulk density of 11.18 g/cm³ (an iron-enriched, high-compression rocky core), a surface gravity of 5.47 g⊕ (53.64 m/s²), and an escape velocity of 43 km/s.
In its orbital architecture around Kepler-32, Kepler-32 d completes one full revolution every 22.78 Earth days at a semi-major axis of 0.13 AU (orbiting interior to Mercury's 0.387 AU benchmark in the Solar System). Its mean orbital velocity is approximately 62.1 km/s (compared to Earth's 29.8 km/s). The orbit is modeled as circular (e = 0.00), maintaining a constant stellar distance throughout its year.
☁️ Atmospheric Regime (Volatile / Gas Envelope): With a radius of 2.700 R⊕, Kepler-32 d 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 Kepler-32 is classified as a low-mass red dwarf of spectral type M1 V with an effective photospheric temperature of 3,900 K, a radius of 0.53 R☉, a mass of 0.58 M☉, an estimated bolometric luminosity of 0.058 L☉. Stellar evolution modeling indicates an estimated stellar age of 5.6 Gyr and a metallicity of [Fe/H] = 0 dex (near-solar heavy-element abundance). From Earth, Kepler-32 shines at apparent V-band magnitude 16.36 (faint and requiring research-grade or CCD telescopic photometry) in the Northern celestial hemisphere. The Kepler-32 system is a multi-planet architecture hosting 5 confirmed worlds, with Kepler-32 d sharing its stellar neighborhood alongside Kepler-32 f, Kepler-32 e, Kepler-32 b, Kepler-32 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: Kepler · Catalogue Source: NASA Exoplanet Archive (IPAC / Caltech).
☀️ Host Star Telemetry
| Host Star Name | Kepler-32 |
| Spectral Type | M1 V |
| Effective Temp (Teff) | 3,900 K |
| Stellar Radius | 0.5300 R☉ |
| Stellar Mass | 0.5800 M☉ |
| Bolometric Luminosity | 0.058 L☉ |
| Metallicity [Fe/H] | 0.000 dex |
| Stellar Age | 5.600 Gyr |
| Apparent Magnitude | V: 16.360 · G: 15.812 |
| System Architecture | 1 Star, 5 Planets |
🪐 Orbital & Physical Dynamics
| Semi-Major Axis (a) | 0.130000 AU |
| Orbital Period | 22.78 days |
| Mean Orbital Velocity | 62.1 km/s |
| Orbital Eccentricity (e) | 0.00000 |
| Orbital Inclination (i) | 89.9900° |
| Mean Bulk Density | 11.18 g/cm³ (43 km/s vesc) |
| Insolation Flux | 3.6310 S⊕ (~4,942 W/m²) |
| Habitable Zone Status | Exterior / Non-HZ |
| Celestial Distance | 1056.200 LY (323.847 pc) |