HIP 109384 b
Astrophysical Synthesis & Habitability Characterization
HIP 109384 b is a confirmed gas giant exoplanet orbiting the star HIP 109384, located approximately 192.3 light-years (58.96 parsecs) from the Solar System. First announced in 2016 by Haute-Provence Observatory using the Radial Velocity detection technique (measuring periodic Doppler reflex motion in the host star's spectrum), this world measures 13.5 Earth radii (1.2 Jupiter radii) and has a measured mass of 495.815 Earth masses (1.56 Jupiter masses). Combining its mass and radius yields a mean bulk density of 1.11 g/cm³ (a low bulk density dominated by an extended hydrogen-helium gaseous envelope), a surface gravity of 2.72 g⊕ (26.67 m/s²), and an escape velocity of 67.8 km/s.
In its orbital architecture around HIP 109384, HIP 109384 b completes one full revolution every 499.48 Earth days (1.37Julian years) at a semi-major axis of 1.134 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 24.7 km/s (compared to Earth's 29.8 km/s). The planet follows a highly eccentric trajectory (e = 0.549, swinging from 0.5114 AU at periapsis out to 1.7566 AU at apoapsis), pointing to past dynamical scattering or secular gravitational perturbations.
☁️ Atmospheric Regime (Volatile / Gas Envelope): With a radius of 13.500 R⊕, HIP 109384 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 HIP 109384 is classified as a solar-type yellow star of spectral type G5 with an effective photospheric temperature of 5,180 K, a radius of 0.8311 R☉, a mass of 0.78 M☉, an estimated bolometric luminosity of 0.446 L☉. Stellar evolution modeling indicates a metallicity of [Fe/H] = -0.26 dex (metal-poor relative to the Sun). From Earth, HIP 109384 shines at apparent V-band magnitude 9.61 (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 | HIP 109384 |
| Spectral Type | G5 |
| Effective Temp (Teff) | 5,180 K |
| Stellar Radius | 0.8311 R☉ |
| Stellar Mass | 0.7800 M☉ |
| Bolometric Luminosity | 0.446 L☉ |
| Metallicity [Fe/H] | -0.260 dex |
| Stellar Age | — |
| Apparent Magnitude | V: 9.610 · G: 9.388 |
| System Architecture | 1 Star, 1 Planet |
🪐 Orbital & Physical Dynamics
| Semi-Major Axis (a) | 1.134000 AU |
| Orbital Period | 499.48 days |
| Mean Orbital Velocity | 24.7 km/s |
| Orbital Eccentricity (e) | 0.54900 |
| Orbital Inclination (i) | — |
| Mean Bulk Density | 1.11 g/cm³ (67.8 km/s vesc) |
| Insolation Flux | 0.3732 S⊕ (~508 W/m²) |
| Habitable Zone Status | Exterior / Non-HZ |
| Celestial Distance | 192.300 LY (58.958 pc) |