HD 108202 b
Astrophysical Synthesis & Habitability Characterization
HD 108202 b is a confirmed gas giant exoplanet orbiting the star HD 108202, located approximately 126.2 light-years (38.69 parsecs) from the Solar System. First announced in 2023 by La Silla Observatory 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 953.485 Earth masses (3 Jupiter masses). Combining its mass and radius yields a mean bulk density of 2.34 g/cm³ (an intermediate density indicative of a deep water-ice mantle or dense volatile envelope), a surface gravity of 5.56 g⊕ (54.52 m/s²), and an escape velocity of 95.4 km/s.
In its orbital architecture around HD 108202, HD 108202 b completes one full revolution every 2990 Earth days (8.19Julian years) at a semi-major axis of 3.7 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 13.5 km/s (compared to Earth's 29.8 km/s). The planet follows a highly eccentric trajectory (e = 0.52, swinging from 1.776 AU at periapsis out to 5.624 AU at apoapsis), pointing to past dynamical scattering or secular gravitational perturbations.
❄️ Thermal Regime (Cryogenic Zone): With an equilibrium temperature of 93 K (-180°C / -292°F) and an incident flux of 0.01 S⊕ (~17 W/m²), surface water and volatile species on HD 108202 b would remain locked in cryogenic ice phases unless warmed by subsurface tidal or radiogenic heating.
The host star HD 108202 is classified as an orange K-type star of spectral type K4/5 V with an effective photospheric temperature of 4,556 K, a radius of 0.6636 R☉, a mass of 0.74 M☉, an estimated bolometric luminosity of 0.17 L☉. Stellar evolution modeling indicates an estimated stellar age of 6.5 Gyr and a metallicity of [Fe/H] = 0.305 dex (metal-rich relative to the Sun). From Earth, HD 108202 shines at apparent V-band magnitude 10.26 (faint and requiring research-grade or CCD telescopic photometry) 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: La Silla Observatory · Catalogue Source: NASA Exoplanet Archive (IPAC / Caltech).
☀️ Host Star Telemetry
| Host Star Name | HD 108202 |
| Spectral Type | K4/5 V |
| Effective Temp (Teff) | 4,556 K |
| Stellar Radius | 0.6636 R☉ |
| Stellar Mass | 0.7400 M☉ |
| Bolometric Luminosity | 0.17 L☉ |
| Metallicity [Fe/H] | 0.305 dex |
| Stellar Age | 6.500 Gyr |
| Apparent Magnitude | V: 10.260 · G: 9.783 |
| System Architecture | 1 Star, 1 Planet |
🪐 Orbital & Physical Dynamics
| Semi-Major Axis (a) | 3.700000 AU |
| Orbital Period | 2990 days |
| Mean Orbital Velocity | 13.5 km/s |
| Orbital Eccentricity (e) | 0.52000 |
| Orbital Inclination (i) | 56.0000° |
| Mean Bulk Density | 2.34 g/cm³ (95.4 km/s vesc) |
| Insolation Flux | 0.0125 S⊕ (~17 W/m²) |
| Habitable Zone Status | Exterior / Non-HZ |
| Celestial Distance | 126.200 LY (38.685 pc) |