HD 181433 c

Astrophysical Synthesis & Habitability Characterization

HD 181433 c is a confirmed gas giant exoplanet orbiting the star HD 181433, located approximately 87.7 light-years (26.88 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 has a minimum or true mass of 2207 Earth masses (6.94 M♃), while its physical transit radius has not yet been geometrically observed.

In its orbital architecture around HD 181433, HD 181433 c completes one full revolution every 1018.5 Earth days (2.79Julian years) at a semi-major axis of 1.885 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 20.1 km/s (compared to Earth's 29.8 km/s). Its moderate orbital eccentricity of e = 0.2402 carries the world between 1.4322 AU at periapsis and 2.3378 AU at apoapsis, driving measurable seasonal insolation cycles.

❄️ Thermal Regime (Cryogenic Zone): With an equilibrium temperature of 154 K (-119°C / -182°F) and an incident flux of 0.10 S⊕ (~134 W/m²), surface water and volatile species on HD 181433 c would remain locked in cryogenic ice phases unless warmed by subsurface tidal or radiogenic heating.

The host star HD 181433 is classified as an orange K-type star of spectral type K3 IV with an effective photospheric temperature of 4,918 K, a radius of 0.79 R☉, a mass of 0.86 M☉, an estimated bolometric luminosity of 0.328 L☉. Stellar evolution modeling indicates an estimated stellar age of 6.7 Gyr and a metallicity of [Fe/H] = 0.401 dex (metal-rich relative to the Sun). From Earth, HD 181433 shines at apparent V-band magnitude 8.4 (accessible to binoculars and small amateur telescopes) in the Southern celestial hemisphere. The HD 181433 system is a multi-planet architecture hosting 3 confirmed worlds, with HD 181433 c sharing its stellar neighborhood alongside HD 181433 b, HD 181433 d.

Discovery Facility: La Silla Observatory · Catalogue Source: NASA Exoplanet Archive (IPAC / Caltech).