HD 47186 c
Astrophysical Synthesis & Habitability Characterization
HD 47186 c is a confirmed gas giant exoplanet orbiting the star HD 47186, located approximately 122.2 light-years (37.46 parsecs) from the Solar System. First announced in 2008 by La Silla Observatory using the Radial Velocity detection technique (measuring periodic Doppler reflex motion in the host star's spectrum), this world measures 13 Earth radii (1.16 Jupiter radii) and has a measured mass of 111.42 Earth masses (0.35 Jupiter masses). Combining its mass and radius yields a mean bulk density of 0.28 g/cm³ (a low bulk density dominated by an extended hydrogen-helium gaseous envelope), a surface gravity of 0.66 g⊕ (6.47 m/s²), and an escape velocity of 32.7 km/s.
In its orbital architecture around HD 47186, HD 47186 c completes one full revolution every 1353.6 Earth days (3.71Julian years) at a semi-major axis of 2.395 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 19.2 km/s (compared to Earth's 29.8 km/s). Its moderate orbital eccentricity of e = 0.249 carries the world between 1.7986 AU at periapsis and 2.9914 AU at apoapsis, driving measurable seasonal insolation cycles.
☁️ Atmospheric Regime (Volatile / Gas Envelope): With a radius of 13.000 R⊕, HD 47186 c 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 47186 is classified as a solar-type yellow star of spectral type G6 V with an effective photospheric temperature of 5,657 K, a radius of 1.08 R☉, a mass of 0.96 M☉, an estimated bolometric luminosity of 1.072 L☉. Stellar evolution modeling indicates an estimated stellar age of 6.5 Gyr and a metallicity of [Fe/H] = 0.24 dex (metal-rich relative to the Sun). From Earth, HD 47186 shines at apparent V-band magnitude 7.63 (accessible to binoculars and small amateur telescopes) in the Southern celestial hemisphere. The HD 47186 system is a multi-planet architecture hosting 2 confirmed worlds, with HD 47186 c sharing its stellar neighborhood alongside HD 47186 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: La Silla Observatory · Catalogue Source: NASA Exoplanet Archive (IPAC / Caltech).
☀️ Host Star Telemetry
| Host Star Name | HD 47186 |
| Spectral Type | G6 V |
| Effective Temp (Teff) | 5,657 K |
| Stellar Radius | 1.0800 R☉ |
| Stellar Mass | 0.9600 M☉ |
| Bolometric Luminosity | 1.072 L☉ |
| Metallicity [Fe/H] | 0.240 dex |
| Stellar Age | 6.500 Gyr |
| Apparent Magnitude | V: 7.630 · G: 7.449 |
| System Architecture | 1 Star, 2 Planets |
🪐 Orbital & Physical Dynamics
| Semi-Major Axis (a) | 2.395000 AU |
| Orbital Period | 1353.6 days |
| Mean Orbital Velocity | 19.2 km/s |
| Orbital Eccentricity (e) | 0.24900 |
| Orbital Inclination (i) | — |
| Mean Bulk Density | 0.28 g/cm³ (32.7 km/s vesc) |
| Insolation Flux | 0.1925 S⊕ (~262 W/m²) |
| Habitable Zone Status | Exterior / Non-HZ |
| Celestial Distance | 122.200 LY (37.457 pc) |