HD 160691 b

Astrophysical Synthesis & Habitability Characterization

HD 160691 b is a confirmed gas giant exoplanet orbiting the star HD 160691, located approximately 50.9 light-years (15.6 parsecs) from the Solar System. First announced in 2000 by Anglo-Australian Telescope 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 1366.662 Earth masses (4.3 M♃), while its physical transit radius has not yet been geometrically observed.

In its orbital architecture around HD 160691, HD 160691 b completes one full revolution every 645 Earth days (1.77Julian years) at a semi-major axis of 1.5 AU (comparable to the inner terrestrial zone between Venus, Earth at 1.00 AU, and Mars at 1.52 AU). Its mean orbital velocity is approximately 25.3 km/s (compared to Earth's 29.8 km/s). Its moderate orbital eccentricity of e = 0.0505 carries the world between 1.4243 AU at periapsis and 1.5758 AU at apoapsis, driving measurable seasonal insolation cycles.

✓ Classified as a Temperate Habitable Zone Candidate.

With an estimated equilibrium temperature of 262 K (-11°C / +12°F) and an incident stellar irradiance of 0.84 S⊕ (~1,149 W/m²), HD 160691 b orbits within the empirical circumstellar habitable zone where a rocky surface under sufficient atmospheric pressure can maintain liquid surface water.

The host star HD 160691 is classified as a solar-type yellow star of spectral type G3 IV-V with an effective photospheric temperature of 5,773 K, a radius of 1.33 R☉, a mass of 1.13 M☉, an estimated bolometric luminosity of 1.763 L☉. Stellar evolution modeling indicates an estimated stellar age of 5.7 Gyr and a metallicity of [Fe/H] = 0.28 dex (metal-rich relative to the Sun). From Earth, HD 160691 shines at apparent V-band magnitude 5.12 (visible to the unaided human eye under dark skies) in the Southern celestial hemisphere. The HD 160691 system is a multi-planet architecture hosting 4 confirmed worlds, with HD 160691 b sharing its stellar neighborhood alongside HD 160691 d, HD 160691 e, HD 160691 c.

Discovery Facility: Anglo-Australian Telescope · Catalogue Source: NASA Exoplanet Archive (IPAC / Caltech).