HD 105779 b
Astrophysical Synthesis & Habitability Characterization
HD 105779 b is a confirmed gas giant exoplanet orbiting the star HD 105779, located approximately 180.2 light-years (55.24 parsecs) from the Solar System. First announced in 2022 by La Silla Observatory using the Radial Velocity detection technique (measuring periodic Doppler reflex motion in the host star's spectrum), this world measures 14.1 Earth radii (1.26 Jupiter radii) and has a measured mass of 203.41 Earth masses (0.64 Jupiter masses). Combining its mass and radius yields a mean bulk density of 0.4 g/cm³ (a low bulk density dominated by an extended hydrogen-helium gaseous envelope), a surface gravity of 1.02 g⊕ (10 m/s²), and an escape velocity of 42.5 km/s.
In its orbital architecture around HD 105779, HD 105779 b completes one full revolution every 2412 Earth days (6.6Julian years) at a semi-major axis of 3.38 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 15.2 km/s (compared to Earth's 29.8 km/s). The orbit is modeled as circular (e = 0.00), maintaining a constant stellar distance throughout its year.
❄️ Thermal Regime (Cryogenic Zone): With an equilibrium temperature of 147 K (-126°C / -195°F) and an incident flux of 0.07 S⊕ (~93 W/m²), surface water and volatile species on HD 105779 b would remain locked in cryogenic ice phases unless warmed by subsurface tidal or radiogenic heating.
The host star HD 105779 is classified as a solar-type yellow star of spectral type G2 with an effective photospheric temperature of 5,792 K, a radius of 0.94 R☉, a mass of 0.89 M☉, an estimated bolometric luminosity of 0.892 L☉. Stellar evolution modeling indicates an estimated stellar age of 7.54 Gyr and a metallicity of [Fe/H] = -0.25 dex (metal-poor relative to the Sun). From Earth, HD 105779 shines at apparent V-band magnitude 8.65 (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 105779 |
| Spectral Type | G2 |
| Effective Temp (Teff) | 5,792 K |
| Stellar Radius | 0.9400 R☉ |
| Stellar Mass | 0.8900 M☉ |
| Bolometric Luminosity | 0.892 L☉ |
| Metallicity [Fe/H] | -0.250 dex |
| Stellar Age | 7.540 Gyr |
| Apparent Magnitude | V: 8.650 · G: 8.490 |
| System Architecture | 1 Star, 1 Planet |
🪐 Orbital & Physical Dynamics
| Semi-Major Axis (a) | 3.380000 AU |
| Orbital Period | 2412 days |
| Mean Orbital Velocity | 15.2 km/s |
| Orbital Eccentricity (e) | 0.00000 |
| Orbital Inclination (i) | — |
| Mean Bulk Density | 0.4 g/cm³ (42.5 km/s vesc) |
| Insolation Flux | 0.0683 S⊕ (~93 W/m²) |
| Habitable Zone Status | Exterior / Non-HZ |
| Celestial Distance | 180.200 LY (55.241 pc) |