HD 3765 b
Astrophysical Synthesis & Habitability Characterization
HD 3765 b is a confirmed gas giant exoplanet orbiting the star HD 3765, located approximately 58.5 light-years (17.93 parsecs) from the Solar System. First announced in 2021 by Multiple Observatories using the Radial Velocity detection technique (measuring periodic Doppler reflex motion in the host star's spectrum), this world measures 8.56 Earth radii (0.76 Jupiter radii) and has a measured mass of 54.984 Earth masses (0.17 Jupiter masses). Combining its mass and radius yields a mean bulk density of 0.48 g/cm³ (a low bulk density dominated by an extended hydrogen-helium gaseous envelope), a surface gravity of 0.75 g⊕ (7.35 m/s²), and an escape velocity of 28.4 km/s.
In its orbital architecture around HD 3765, HD 3765 b completes one full revolution every 1211 Earth days (3.32Julian years) at a semi-major axis of 2.108 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 18.9 km/s (compared to Earth's 29.8 km/s). The planet follows a highly eccentric trajectory (e = 0.298, swinging from 1.4798 AU at periapsis out to 2.7362 AU at apoapsis), pointing to past dynamical scattering or secular gravitational perturbations.
❄️ Thermal Regime (Cryogenic Zone): With an equilibrium temperature of 153 K (-120°C / -184°F) and an incident flux of 0.09 S⊕ (~117 W/m²), surface water and volatile species on HD 3765 b would remain locked in cryogenic ice phases unless warmed by subsurface tidal or radiogenic heating.
The host star HD 3765 is classified as an orange K-type star of spectral type K2V with an effective photospheric temperature of 5,050 K, a radius of 0.8306 R☉, a mass of 0.8518 M☉, an estimated bolometric luminosity of 0.403 L☉. Stellar evolution modeling indicates an estimated stellar age of 2 Gyr and a metallicity of [Fe/H] = 0.172 dex (metal-rich relative to the Sun). From Earth, HD 3765 shines at apparent V-band magnitude 7.36 (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: Multiple Observatories · Catalogue Source: NASA Exoplanet Archive (IPAC / Caltech).
☀️ Host Star Telemetry
| Host Star Name | HD 3765 |
| Spectral Type | K2V |
| Effective Temp (Teff) | 5,050 K |
| Stellar Radius | 0.8306 R☉ |
| Stellar Mass | 0.8518 M☉ |
| Bolometric Luminosity | 0.403 L☉ |
| Metallicity [Fe/H] | 0.172 dex |
| Stellar Age | 2.000 Gyr |
| Apparent Magnitude | V: 7.360 · G: 7.078 |
| System Architecture | 1 Star, 1 Planet |
🪐 Orbital & Physical Dynamics
| Semi-Major Axis (a) | 2.108000 AU |
| Orbital Period | 1211 days |
| Mean Orbital Velocity | 18.9 km/s |
| Orbital Eccentricity (e) | 0.29800 |
| Orbital Inclination (i) | — |
| Mean Bulk Density | 0.48 g/cm³ (28.4 km/s vesc) |
| Insolation Flux | 0.0863 S⊕ (~117 W/m²) |
| Habitable Zone Status | Exterior / Non-HZ |
| Celestial Distance | 58.500 LY (17.926 pc) |