HD 185269 b
Astrophysical Synthesis & Habitability Characterization
HD 185269 b is a confirmed gas giant exoplanet orbiting the star HD 185269, located approximately 169.6 light-years (51.99 parsecs) from the Solar System. First announced in 2006 by Lick Observatory using the Radial Velocity detection technique (measuring periodic Doppler reflex motion in the host star's spectrum), this world measures 13.8 Earth radii (1.23 Jupiter radii) and has a measured mass of 321.008 Earth masses (1.01 Jupiter masses). Combining its mass and radius yields a mean bulk density of 0.67 g/cm³ (a low bulk density dominated by an extended hydrogen-helium gaseous envelope), a surface gravity of 1.69 g⊕ (16.57 m/s²), and an escape velocity of 54 km/s.
In its orbital architecture around HD 185269, HD 185269 b completes one full revolution every 6.838 Earth days at a semi-major axis of 0.077 AU (orbiting interior to Mercury's 0.387 AU benchmark in the Solar System). Its mean orbital velocity is approximately 122.5 km/s (compared to Earth's 29.8 km/s). Its moderate orbital eccentricity of e = 0.229 carries the world between 0.0594 AU at periapsis and 0.0946 AU at apoapsis, driving measurable seasonal insolation cycles.
⚠️ Thermal Regime (Irradiated / Hot Zone): At an equilibrium temperature of 1456 K (+1183°C / +2161°F) and receiving 832.98 S⊕ (~1,133,689 W/m²), HD 185269 b orbits interior to the runaway greenhouse boundary where surface liquid water cannot persist.
The host star HD 185269 is classified as a solar-type yellow star of spectral type G0 IV with an effective photospheric temperature of 5,923 K, a radius of 2 R☉, a mass of 1.3 M☉, an estimated bolometric luminosity of 4.417 L☉. Stellar evolution modeling indicates an estimated stellar age of 4 Gyr and a metallicity of [Fe/H] = 0.11 dex (metal-rich relative to the Sun). From Earth, HD 185269 shines at apparent V-band magnitude 6.68 (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: Lick Observatory · Catalogue Source: NASA Exoplanet Archive (IPAC / Caltech).
☀️ Host Star Telemetry
| Host Star Name | HD 185269 |
| Spectral Type | G0 IV |
| Effective Temp (Teff) | 5,923 K |
| Stellar Radius | 2.0000 R☉ |
| Stellar Mass | 1.3000 M☉ |
| Bolometric Luminosity | 4.417 L☉ |
| Metallicity [Fe/H] | 0.110 dex |
| Stellar Age | 4.000 Gyr |
| Apparent Magnitude | V: 6.680 · G: 6.518 |
| System Architecture | 3 Stars, 1 Planet |
🪐 Orbital & Physical Dynamics
| Semi-Major Axis (a) | 0.077000 AU |
| Orbital Period | 6.838 days |
| Mean Orbital Velocity | 122.5 km/s |
| Orbital Eccentricity (e) | 0.22900 |
| Orbital Inclination (i) | — |
| Mean Bulk Density | 0.67 g/cm³ (54 km/s vesc) |
| Insolation Flux | 832.9821 S⊕ (~1,133,689 W/m²) |
| Habitable Zone Status | Exterior / Non-HZ |
| Celestial Distance | 169.600 LY (51.992 pc) |