HD 331093 b
Astrophysical Synthesis & Habitability Characterization
HD 331093 b is a confirmed gas giant exoplanet orbiting the star HD 331093, located approximately 163.7 light-years (50.19 parsecs) from the Solar System. First announced in 2021 by Haute-Provence Observatory using the Radial Velocity detection technique (measuring periodic Doppler reflex motion in the host star's spectrum), this world measures 13.6 Earth radii (1.21 Jupiter radii) and has a measured mass of 476.743 Earth masses (1.5 Jupiter masses). Combining its mass and radius yields a mean bulk density of 1.05 g/cm³ (a low bulk density dominated by an extended hydrogen-helium gaseous envelope), a surface gravity of 2.58 g⊕ (25.3 m/s²), and an escape velocity of 66.2 km/s.
In its orbital architecture around HD 331093, HD 331093 b completes one full revolution every 621.62 Earth days (1.7Julian years) at a semi-major axis of 1.44 AU (comparable to the inner terrestrial zone between Venus, Earth at 1.00 AU, and Mars at 1.52 AU). Its mean orbital velocity is approximately 25.2 km/s (compared to Earth's 29.8 km/s). The planet follows a highly eccentric trajectory (e = 0.59, swinging from 0.5904 AU at periapsis out to 2.2896 AU at apoapsis), pointing to past dynamical scattering or secular gravitational perturbations.
☁️ Atmospheric Regime (Volatile / Gas Envelope): With a radius of 13.600 R⊕, HD 331093 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 331093 is classified as an orange K-type star of spectral type K0 with an effective photospheric temperature of 5,544 K, a radius of 1.1112 R☉, a mass of 1.03 M☉, an estimated bolometric luminosity of 1.047 L☉. Stellar evolution modeling indicates a metallicity of [Fe/H] = 0.17 dex (metal-rich relative to the Sun). From Earth, HD 331093 shines at apparent V-band magnitude 8.38 (accessible to binoculars and small amateur telescopes) in the Northern 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: Haute-Provence Observatory · Catalogue Source: NASA Exoplanet Archive (IPAC / Caltech).
☀️ Host Star Telemetry
| Host Star Name | HD 331093 |
| Spectral Type | K0 |
| Effective Temp (Teff) | 5,544 K |
| Stellar Radius | 1.1112 R☉ |
| Stellar Mass | 1.0300 M☉ |
| Bolometric Luminosity | 1.047 L☉ |
| Metallicity [Fe/H] | 0.170 dex |
| Stellar Age | — |
| Apparent Magnitude | V: 8.380 · G: 8.191 |
| System Architecture | 1 Star, 1 Planet |
🪐 Orbital & Physical Dynamics
| Semi-Major Axis (a) | 1.440000 AU |
| Orbital Period | 621.62 days |
| Mean Orbital Velocity | 25.2 km/s |
| Orbital Eccentricity (e) | 0.59000 |
| Orbital Inclination (i) | 0.3704° |
| Mean Bulk Density | 1.05 g/cm³ (66.2 km/s vesc) |
| Insolation Flux | 0.4895 S⊕ (~666 W/m²) |
| Habitable Zone Status | Exterior / Non-HZ |
| Celestial Distance | 163.700 LY (50.193 pc) |