HD 28185 c
Astrophysical Synthesis & Habitability Characterization
HD 28185 c is a confirmed gas giant exoplanet orbiting the star HD 28185, located approximately 128.4 light-years (39.38 parsecs) from the Solar System. First announced in 2022 by Multiple Observatories using the Radial Velocity detection technique (measuring periodic Doppler reflex motion in the host star's spectrum), this world measures 12.8 Earth radii (1.14 Jupiter radii) and has a measured mass of 1906.97 Earth masses (6 Jupiter masses). Combining its mass and radius yields a mean bulk density of 5.01 g/cm³ (a terrestrial silicate-iron composition comparable to Earth (5.51 g/cm³)), a surface gravity of 11.64 g⊕ (114.15 m/s²), and an escape velocity of 136.5 km/s.
In its orbital architecture around HD 28185, HD 28185 c completes one full revolution every 9090 Earth days (24.89Julian years) at a semi-major axis of 8.5 AU (a wide outer-system orbit beyond Jupiter's 5.20 AU distance in our Solar System). Its mean orbital velocity is approximately 10.2 km/s (compared to Earth's 29.8 km/s). Its moderate orbital eccentricity of e = 0.15 carries the world between 7.225 AU at periapsis and 9.775 AU at apoapsis, driving measurable seasonal insolation cycles.
❄️ Thermal Regime (Cryogenic Zone): With an equilibrium temperature of 95 K (-178°C / -288°F) and an incident flux of 0.01 S⊕ (~18 W/m²), surface water and volatile species on HD 28185 c would remain locked in cryogenic ice phases unless warmed by subsurface tidal or radiogenic heating.
The host star HD 28185 is classified as a solar-type yellow star of spectral type G5 with an effective photospheric temperature of 5,602 K, a radius of 1.048 R☉, a mass of 0.974 M☉, an estimated bolometric luminosity of 0.97 L☉. Stellar evolution modeling indicates an estimated stellar age of 8.3 Gyr and a metallicity of [Fe/H] = 0.19 dex (metal-rich relative to the Sun). From Earth, HD 28185 shines at apparent V-band magnitude 7.8 (accessible to binoculars and small amateur telescopes) in the Southern celestial hemisphere. The HD 28185 system is a multi-planet architecture hosting 2 confirmed worlds, with HD 28185 c sharing its stellar neighborhood alongside HD 28185 b.
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 28185 |
| Spectral Type | G5 |
| Effective Temp (Teff) | 5,602 K |
| Stellar Radius | 1.0480 R☉ |
| Stellar Mass | 0.9740 M☉ |
| Bolometric Luminosity | 0.97 L☉ |
| Metallicity [Fe/H] | 0.190 dex |
| Stellar Age | 8.300 Gyr |
| Apparent Magnitude | V: 7.800 · G: 7.627 |
| System Architecture | 1 Star, 2 Planets |
🪐 Orbital & Physical Dynamics
| Semi-Major Axis (a) | 8.500000 AU |
| Orbital Period | 9090 days |
| Mean Orbital Velocity | 10.2 km/s |
| Orbital Eccentricity (e) | 0.15000 |
| Orbital Inclination (i) | 66.0000° |
| Mean Bulk Density | 5.01 g/cm³ (136.5 km/s vesc) |
| Insolation Flux | 0.0134 S⊕ (~18 W/m²) |
| Habitable Zone Status | Exterior / Non-HZ |
| Celestial Distance | 128.400 LY (39.381 pc) |