Kepler-732 b
Astrophysical Synthesis & Habitability Characterization
Kepler-732 b is a confirmed sub-neptune exoplanet orbiting the star Kepler-732, located approximately 570.2 light-years (174.83 parsecs) from the Solar System. First announced in 2016 by Kepler using the Transit detection technique (producing an estimated primary transit depth of 0.1888% across the stellar disk), this world measures 2.18 Earth radii and has a measured mass of 5.39 Earth masses. Combining its mass and radius yields a mean bulk density of 2.87 g/cm³ (an intermediate density indicative of a deep water-ice mantle or dense volatile envelope), a surface gravity of 1.13 g⊕ (11.08 m/s²), and an escape velocity of 17.6 km/s.
In its orbital architecture around Kepler-732, Kepler-732 b completes one full revolution every 9.468 Earth days at a semi-major axis of 0.0691 AU (orbiting interior to Mercury's 0.387 AU benchmark in the Solar System). Its mean orbital velocity is approximately 79.4 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.
⚠️ Thermal Regime (Irradiated / Hot Zone): At an equilibrium temperature of 407 K (+134°C / +273°F) and receiving 8.56 S⊕ (~11,649 W/m²), Kepler-732 b orbits interior to the runaway greenhouse boundary where surface liquid water cannot persist.
The host star Kepler-732 is classified as a stellar host with an effective photospheric temperature of 3,631 K, a radius of 0.46 R☉, a mass of 0.49 M☉, an estimated bolometric luminosity of 0.033 L☉. Stellar evolution modeling indicates an estimated stellar age of 4.47 Gyr and a metallicity of [Fe/H] = -0.01 dex (near-solar heavy-element abundance). From Earth, Kepler-732 shines at apparent V-band magnitude 16.53 (faint and requiring research-grade or CCD telescopic photometry) in the Northern celestial hemisphere. The Kepler-732 system is a multi-planet architecture hosting 2 confirmed worlds, with Kepler-732 b sharing its stellar neighborhood alongside Kepler-732 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-732 |
| Spectral Type | Unclassified |
| Effective Temp (Teff) | 3,631 K |
| Stellar Radius | 0.4600 R☉ |
| Stellar Mass | 0.4900 M☉ |
| Bolometric Luminosity | 0.033 L☉ |
| Metallicity [Fe/H] | -0.010 dex |
| Stellar Age | 4.470 Gyr |
| Apparent Magnitude | V: 16.530 · G: 15.052 |
| System Architecture | 1 Star, 2 Planets |
🪐 Orbital & Physical Dynamics
| Semi-Major Axis (a) | 0.069100 AU |
| Orbital Period | 9.468 days |
| Mean Orbital Velocity | 79.4 km/s |
| Orbital Eccentricity (e) | 0.00000 |
| Orbital Inclination (i) | 89.8500° |
| Mean Bulk Density | 2.87 g/cm³ (17.6 km/s vesc) |
| Insolation Flux | 8.5590 S⊕ (~11,649 W/m²) |
| Habitable Zone Status | Exterior / Non-HZ |
| Celestial Distance | 570.200 LY (174.826 pc) |