Revealing the Fate of Exoplanet Systems: Asteroseismic Identification of Host Star in the Red Clump or Red Giant Branch

TL;DR

This study uses asteroseismology with TESS data to accurately determine the evolutionary stages of two exoplanet-hosting stars, revealing their status as Red Clump or Red Giant Branch stars, which is vital for understanding planetary system evolution.

Contribution

It presents the first asteroseismic confirmation of the evolutionary stages of HD 120084 and HD 29399, demonstrating automated measurement techniques for stellar evolution analysis.

Findings

HD 120084 is a Red Clump star in helium-core burning.

HD 29399 is a Red Giant Branch star in hydrogen-shell burning.

Asteroseismic parameters enable precise stellar evolutionary classification.

Abstract

Determining the evolutionary stage of stars is crucial for understanding the evolution of exoplanetary systems. In this context, Red Giant Branch (RGB) and Red Clump (RC) stars, stages in the later evolution of stars situated before and after the helium flash, harbor critical clues to unveiling the evolution of planets. The first step in revealing these clues is to confirm the evolutionary stage of the host stars through asteroseismology. However, up to now, host stars confirmed to be RGB or RC stars are extremely rare. In this investigation, we present a comprehensive asteroseismic analysis of two evolved stars, HD 120084 and HD 29399, known to harbor exoplanets, using data from the Transiting Exoplanet Survey Satellite (TESS). We have discovered for the first time that HD 120084 is a Red Clump star in the helium-core burning phase, and confirmed that HD 29399 is a Red Giant Branch star in the hydrogen-shell burning phase. Through the precise measurement of asteroseismic parameters such as $\nu_{max}$, $\Delta\nu$ and $\Delta\Pi_{1}$ we have determined the evolutionary states of these stars and derived their fundamental stellar parameters. The significance of this study lies in the application of automated techniques to measure asymptotic period spacings in red giants, which provides critical insights into the evolutionary outcomes of exoplanet systems. We demonstrate that asteroseismology is a potent tool for probing the internal structures of stars, thereby offering a window into the past and future dynamics of planetary orbits. The presence of a long-period giant planet orbiting HD 120084, in particular, raises intriguing questions about the potential engulfment of inner planets during the host star's expansion, a hypothesis that warrants further investigation.