HD 216437 b
Astrophysical Synthesis & Habitability Characterization
HD 216437 b is a confirmed gas giant exoplanet orbiting the star HD 216437, located approximately 87.1 light-years (26.69 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 Earth radii (1.16 Jupiter radii) and has a measured mass of 1334.879 Earth masses (4.2 Jupiter masses). Combining its mass and radius yields a mean bulk density of 3.35 g/cm³ (an intermediate density indicative of a deep water-ice mantle or dense volatile envelope), a surface gravity of 7.9 g⊕ (77.47 m/s²), and an escape velocity of 113.4 km/s.
In its orbital architecture around HD 216437, HD 216437 b completes one full revolution every 1359 Earth days (3.72Julian years) at a semi-major axis of 2.57 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 20.6 km/s (compared to Earth's 29.8 km/s). The planet follows a highly eccentric trajectory (e = 0.31, swinging from 1.7733 AU at periapsis out to 3.3667 AU at apoapsis), pointing to past dynamical scattering or secular gravitational perturbations.
☁️ Atmospheric Regime (Volatile / Gas Envelope): With a radius of 13.000 R⊕, HD 216437 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 216437 is classified as a solar-type yellow star of spectral type G1 V with an effective photospheric temperature of 5,909 K, a radius of 1.394 R☉, a mass of 1.22 M☉, an estimated bolometric luminosity of 2.126 L☉. Stellar evolution modeling indicates an estimated stellar age of 4.9 Gyr and a metallicity of [Fe/H] = 0.2 dex (metal-rich relative to the Sun). From Earth, HD 216437 shines at apparent V-band magnitude 6.04 (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 216437 |
| Spectral Type | G1 V |
| Effective Temp (Teff) | 5,909 K |
| Stellar Radius | 1.3940 R☉ |
| Stellar Mass | 1.2200 M☉ |
| Bolometric Luminosity | 2.126 L☉ |
| Metallicity [Fe/H] | 0.200 dex |
| Stellar Age | 4.900 Gyr |
| Apparent Magnitude | V: 6.040 · G: 5.894 |
| System Architecture | 1 Star, 1 Planet |
🪐 Orbital & Physical Dynamics
| Semi-Major Axis (a) | 2.570000 AU |
| Orbital Period | 1359 days |
| Mean Orbital Velocity | 20.6 km/s |
| Orbital Eccentricity (e) | 0.31000 |
| Orbital Inclination (i) | 148.0000° |
| Mean Bulk Density | 3.35 g/cm³ (113.4 km/s vesc) |
| Insolation Flux | 0.3389 S⊕ (~461 W/m²) |
| Habitable Zone Status | Exterior / Non-HZ |
| Celestial Distance | 87.100 LY (26.690 pc) |