HD 215152 d

Astrophysical Synthesis & Habitability Characterization

HD 215152 d is a confirmed gas giant exoplanet orbiting the star HD 215152, located approximately 70.4 light-years (21.6 parsecs) from the Solar System. First announced in 2018 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 770.416 Earth masses (2.42 M♃), while its physical transit radius has not yet been geometrically observed.

In its orbital architecture around HD 215152, HD 215152 d completes one full revolution every 10.865 Earth days at a semi-major axis of 0.08799 AU (orbiting interior to Mercury's 0.387 AU benchmark in the Solar System). Its mean orbital velocity is approximately 88.1 km/s (compared to Earth's 29.8 km/s). The orbit is modeled as circular (e = 0.00), maintaining a constant stellar distance throughout its year.

⚠️ Thermal Regime (Irradiated / Hot Zone): At an equilibrium temperature of 685 K (+412°C / +774°F) and receiving 38.78 S⊕ (~52,778 W/m²), HD 215152 d orbits interior to the runaway greenhouse boundary where surface liquid water cannot persist.

The host star HD 215152 is classified as an orange K-type star of spectral type K3 V with an effective photospheric temperature of 4,935 K, a radius of 0.73 R☉, a mass of 0.77 M☉, an estimated bolometric luminosity of 0.284 L☉. Stellar evolution modeling indicates a metallicity of [Fe/H] = -0.1 dex (near-solar heavy-element abundance). From Earth, HD 215152 shines at apparent V-band magnitude 8.11 (accessible to binoculars and small amateur telescopes) in the Southern celestial hemisphere. The HD 215152 system is a multi-planet architecture hosting 4 confirmed worlds, with HD 215152 d sharing its stellar neighborhood alongside HD 215152 b, HD 215152 c, HD 215152 e.

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