The Pan-Pacific Planet Search VII: The most eccentric planet orbiting a giant star

TL;DR

This paper reports the discovery of the most eccentric planet orbiting an evolved star, HD 76920b, with a highly elongated orbit and potential future engulfment by its host star.

Contribution

It presents the detection and characterization of a highly eccentric exoplanet around a giant star, highlighting its unique orbit and implications for planetary evolution.

Findings

HD 76920b has an eccentricity of 0.856.

The planet is likely to be engulfed in about 100 million years.

No binary companion detected, suggesting scattering as the eccentricity cause.

Abstract

Radial velocity observations from three instruments reveal the presence of a 4 M_jup planet candidate orbiting the K giant HD 76920. HD 76920b has an orbital eccentricity of 0.856$\pm$0.009, making it the most eccentric planet known to orbit an evolved star. There is no indication that HD 76920 has an unseen binary companion, suggesting a scattering event rather than Kozai oscillations as a probable culprit for the observed eccentricity. The candidate planet currently approaches to about four stellar radii from its host star, and is predicted to be engulfed on a $\sim$100 Myr timescale due to the combined effects of stellar evolution and tidal interactions.