Abstract

Contributed Talk - Plenary

Planetary Engulfment and its Impact on Stellar Magnetic Activity in Close-Orbit Systems

Julius Göhring
AIP, University of Potsdam

Close-in exoplanets are not passive companions to their host stars—they can significantly influence stellar evolution through magnetic and tidal interactions, particularly in systems where the planet is ultimately engulfed. When such engulfment occurs, angular momentum from the planet is transferred to the star, potentially spinning it up and enhancing its magnetic activity. This process can alter key stellar observables, such as chromospheric emission and rotation rates, with consequences for age-dating methods like gyrochronology. In this work, I investigate magnetic activity enhancement from suspected planetary engulfment using wide binaries as natural control systems. Chromospheric activity was quantified using multiple spectral indicators, including Hα, the second line of the CaII infrared triplet, and the Na doublet, based on high-resolution spectra from KECK and ESO archives. Activity differences between binary components were evaluated in relation to effective temperature differences. Additionally, simulations of angular momentum transfer and magnetic braking were used to assess whether observed activity patterns can be explained by the engulfment of close-in, low-mass planets. This work demonstrates how differential activity analysis in wide binaries can help distinguish the effects of suspected planetary engulfment from those of standard stellar evolution.