HD 216435 b
Astrophysical Synthesis & Habitability Characterization
HD 216435 b is a confirmed gas giant exoplanet orbiting the star HD 216435, located approximately 107.6 light-years (32.98 parsecs) from the Solar System. First announced in 2002 by Anglo-Australian Telescope using the Radial Velocity detection technique (measuring periodic Doppler reflex motion in the host star's spectrum), this world measures 13.7 Earth radii (1.22 Jupiter radii) and has a measured mass of 400.4 Earth masses (1.26 Jupiter masses). Combining its mass and radius yields a mean bulk density of 0.86 g/cm³ (a low bulk density dominated by an extended hydrogen-helium gaseous envelope), a surface gravity of 2.13 g⊕ (20.89 m/s²), and an escape velocity of 60.5 km/s.
In its orbital architecture around HD 216435, HD 216435 b completes one full revolution every 1311 Earth days (3.59Julian years) at a semi-major axis of 2.56 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 21.2 km/s (compared to Earth's 29.8 km/s). Its moderate orbital eccentricity of e = 0.07 carries the world between 2.3808 AU at periapsis and 2.7392 AU at apoapsis, driving measurable seasonal insolation cycles.
☁️ Atmospheric Regime (Volatile / Gas Envelope): With a radius of 13.700 R⊕, HD 216435 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 HD 216435 is classified as a solar-type yellow star of spectral type G0 V with an effective photospheric temperature of 5,999 K, a radius of 1.8 R☉, a mass of 1.3 M☉, an estimated bolometric luminosity of 3.765 L☉. Stellar evolution modeling indicates an estimated stellar age of 3 Gyr and a metallicity of [Fe/H] = 0.244 dex (metal-rich relative to the Sun). From Earth, HD 216435 shines at apparent V-band magnitude 6.03 (visible to the unaided human eye under dark skies) 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: Anglo-Australian Telescope · Catalogue Source: NASA Exoplanet Archive (IPAC / Caltech).
☀️ Host Star Telemetry
| Host Star Name | HD 216435 |
| Spectral Type | G0 V |
| Effective Temp (Teff) | 5,999 K |
| Stellar Radius | 1.8000 R☉ |
| Stellar Mass | 1.3000 M☉ |
| Bolometric Luminosity | 3.765 L☉ |
| Metallicity [Fe/H] | 0.244 dex |
| Stellar Age | 3.000 Gyr |
| Apparent Magnitude | V: 6.030 · G: 5.884 |
| System Architecture | 1 Star, 1 Planet |
🪐 Orbital & Physical Dynamics
| Semi-Major Axis (a) | 2.560000 AU |
| Orbital Period | 1311 days |
| Mean Orbital Velocity | 21.2 km/s |
| Orbital Eccentricity (e) | 0.07000 |
| Orbital Inclination (i) | — |
| Mean Bulk Density | 0.86 g/cm³ (60.5 km/s vesc) |
| Insolation Flux | 0.5501 S⊕ (~749 W/m²) |
| Habitable Zone Status | Exterior / Non-HZ |
| Celestial Distance | 107.600 LY (32.983 pc) |