Overview

• Astronomers have confirmed the existence of a retrograde planet in the ν Octantis system, orbiting opposite to its stars' mutual revolution.
• The system comprises a sub-giant star 57% heavier than the Sun and a recently identified white dwarf companion 43% lighter.
• Eighteen years of radial velocity data and adaptive optics imaging resolved the planet’s orbit and the binary system’s architecture.
• The planet’s retrograde motion challenges existing models of planet formation in close binaries, where gravitational dynamics typically preclude stability.
• Researchers propose the planet formed from material ejected during the white dwarf’s creation or through migration from a circumbinary disc.