HD 181433 b

Astrophysical Synthesis & Habitability Characterization

HD 181433 b 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 1708.646 Earth masses (5.38 M♃), while its physical transit radius has not yet been geometrically observed.

In its orbital architecture around HD 181433, HD 181433 b completes one full revolution every 9.375 Earth days at a semi-major axis of 0.0828 AU (orbiting interior to Mercury's 0.387 AU benchmark in the Solar System). Its mean orbital velocity is approximately 96.1 km/s (compared to Earth's 29.8 km/s). The planet follows a highly eccentric trajectory (e = 0.396, swinging from 0.05 AU at periapsis out to 0.1156 AU at apoapsis), pointing to past dynamical scattering or secular gravitational perturbations.

⚠️ Thermal Regime (Irradiated / Hot Zone): At an equilibrium temperature of 733 K (+460°C / +860°F) and receiving 51.02 S⊕ (~69,442 W/m²), HD 181433 b orbits interior to the runaway greenhouse boundary where surface liquid water cannot persist.

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 b sharing its stellar neighborhood alongside HD 181433 c, HD 181433 d.

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