HD 4732 c
Astrophysical Synthesis & Habitability Characterization
HD 4732 c is a confirmed gas giant exoplanet orbiting the star HD 4732, located approximately 178.7 light-years (54.78 parsecs) from the Solar System. First announced in 2012 by Multiple Observatories using the Radial Velocity detection technique (measuring periodic Doppler reflex motion in the host star's spectrum), this world measures 13.1 Earth radii (1.17 Jupiter radii) and has a measured mass of 1069.493 Earth masses (3.36 Jupiter masses). Combining its mass and radius yields a mean bulk density of 2.62 g/cm³ (an intermediate density indicative of a deep water-ice mantle or dense volatile envelope), a surface gravity of 6.23 g⊕ (61.1 m/s²), and an escape velocity of 101.1 km/s.
In its orbital architecture around HD 4732, HD 4732 c completes one full revolution every 3184.2 Earth days (8.72Julian years) at a semi-major axis of 4.725 AU (corresponding to the middle-system regime between Mars at 1.52 AU and Jupiter at 5.20 AU). Its mean orbital velocity is approximately 16.1 km/s (compared to Earth's 29.8 km/s). Its moderate orbital eccentricity of e = 0.187 carries the world between 3.8414 AU at periapsis and 5.6086 AU at apoapsis, driving measurable seasonal insolation cycles.
☁️ Atmospheric Regime (Volatile / Gas Envelope): With a radius of 13.100 R⊕, HD 4732 c 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 HD 4732 is classified as an orange K-type star of spectral type K0 IV with an effective photospheric temperature of 4,898 K, a radius of 5.03 R☉, a mass of 1.39 M☉, an estimated bolometric luminosity of 13.065 L☉. Stellar evolution modeling indicates an estimated stellar age of 1.47 Gyr and a metallicity of [Fe/H] = -0.01 dex (near-solar heavy-element abundance). From Earth, HD 4732 shines at apparent V-band magnitude 5.9 (visible to the unaided human eye under dark skies) in the Southern celestial hemisphere. The HD 4732 system is a multi-planet architecture hosting 2 confirmed worlds, with HD 4732 c sharing its stellar neighborhood alongside HD 4732 b.
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: Multiple Observatories · Catalogue Source: NASA Exoplanet Archive (IPAC / Caltech).
☀️ Host Star Telemetry
| Host Star Name | HD 4732 |
| Spectral Type | K0 IV |
| Effective Temp (Teff) | 4,898 K |
| Stellar Radius | 5.0300 R☉ |
| Stellar Mass | 1.3900 M☉ |
| Bolometric Luminosity | 13.065 L☉ |
| Metallicity [Fe/H] | -0.010 dex |
| Stellar Age | 1.470 Gyr |
| Apparent Magnitude | V: 5.900 · G: 5.651 |
| System Architecture | 2 Stars, 2 Planets |
🪐 Orbital & Physical Dynamics
| Semi-Major Axis (a) | 4.725000 AU |
| Orbital Period | 3184.2 days |
| Mean Orbital Velocity | 16.1 km/s |
| Orbital Eccentricity (e) | 0.18700 |
| Orbital Inclination (i) | — |
| Mean Bulk Density | 2.62 g/cm³ (101.1 km/s vesc) |
| Insolation Flux | 0.5881 S⊕ (~800 W/m²) |
| Habitable Zone Status | Exterior / Non-HZ |
| Celestial Distance | 178.700 LY (54.784 pc) |