HD 94771 b
Astrophysical Synthesis & Habitability Characterization
HD 94771 b is a confirmed gas giant exoplanet orbiting the star HD 94771, located approximately 188.5 light-years (57.78 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 14.2 Earth radii (1.27 Jupiter radii) and has a measured mass of 169 Earth masses (0.53 Jupiter masses). Combining its mass and radius yields a mean bulk density of 0.33 g/cm³ (a low bulk density dominated by an extended hydrogen-helium gaseous envelope), a surface gravity of 0.84 g⊕ (8.24 m/s²), and an escape velocity of 38.6 km/s.
In its orbital architecture around HD 94771, HD 94771 b completes one full revolution every 2164 Earth days (5.92Julian years) at a semi-major axis of 3.48 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 17.5 km/s (compared to Earth's 29.8 km/s). The planet follows a highly eccentric trajectory (e = 0.39, swinging from 2.1228 AU at periapsis out to 4.8372 AU at apoapsis), pointing to past dynamical scattering or secular gravitational perturbations.
☁️ Atmospheric Regime (Volatile / Gas Envelope): With a radius of 14.200 R⊕, HD 94771 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 94771 is classified as a solar-type yellow star of spectral type G3/G5 V with an effective photospheric temperature of 5,631 K, a radius of 1.903 R☉, a mass of 1.2 M☉, an estimated bolometric luminosity of 3.267 L☉. Stellar evolution modeling indicates an estimated stellar age of 5.733 Gyr and a metallicity of [Fe/H] = 0.22 dex (metal-rich relative to the Sun). From Earth, HD 94771 shines at apparent V-band magnitude 7.37 (accessible to binoculars and small amateur telescopes) 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 94771 |
| Spectral Type | G3/G5 V |
| Effective Temp (Teff) | 5,631 K |
| Stellar Radius | 1.9030 R☉ |
| Stellar Mass | 1.2000 M☉ |
| Bolometric Luminosity | 3.267 L☉ |
| Metallicity [Fe/H] | 0.220 dex |
| Stellar Age | 5.733 Gyr |
| Apparent Magnitude | V: 7.370 · G: 7.179 |
| System Architecture | 1 Star, 1 Planet |
🪐 Orbital & Physical Dynamics
| Semi-Major Axis (a) | 3.480000 AU |
| Orbital Period | 2164 days |
| Mean Orbital Velocity | 17.5 km/s |
| Orbital Eccentricity (e) | 0.39000 |
| Orbital Inclination (i) | — |
| Mean Bulk Density | 0.33 g/cm³ (38.6 km/s vesc) |
| Insolation Flux | 0.2710 S⊕ (~369 W/m²) |
| Habitable Zone Status | Exterior / Non-HZ |
| Celestial Distance | 188.500 LY (57.781 pc) |