HD 215497 b

Astrophysical Synthesis & Habitability Characterization

HD 215497 b is a confirmed gas giant exoplanet orbiting the star HD 215497, located approximately 132.2 light-years (40.55 parsecs) from the Solar System. First announced in 2009 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 1588.824 Earth masses (5 M♃), while its physical transit radius has not yet been geometrically observed.

In its orbital architecture around HD 215497, HD 215497 b completes one full revolution every 3.934 Earth days at a semi-major axis of 0.05 AU (orbiting interior to Mercury's 0.387 AU benchmark in the Solar System). Its mean orbital velocity is approximately 138.3 km/s (compared to Earth's 29.8 km/s). Its moderate orbital eccentricity of e = 0.16 carries the world between 0.042 AU at periapsis and 0.058 AU at apoapsis, driving measurable seasonal insolation cycles.

⚠️ Thermal Regime (Irradiated / Hot Zone): At an equilibrium temperature of 1016 K (+743°C / +1369°F) and receiving 155.62 S⊕ (~211,796 W/m²), HD 215497 b orbits interior to the runaway greenhouse boundary where surface liquid water cannot persist.

The host star HD 215497 is classified as an orange K-type star of spectral type K3 V with an effective photospheric temperature of 5,110 K, a radius of 0.85 R☉, a mass of 0.67 M☉, an estimated bolometric luminosity of 0.442 L☉. Stellar evolution modeling indicates an estimated stellar age of 5.8 Gyr and a metallicity of [Fe/H] = 0.2 dex (metal-rich relative to the Sun). From Earth, HD 215497 shines at apparent V-band magnitude 8.96 (accessible to binoculars and small amateur telescopes) in the Southern celestial hemisphere. The HD 215497 system is a multi-planet architecture hosting 2 confirmed worlds, with HD 215497 b sharing its stellar neighborhood alongside HD 215497 c.

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