Stellar Photospheric Abundances as a Probe of Disks and Planets

TL;DR

This paper introduces a theoretical framework to interpret stellar photospheric abundances, revealing the composition of accreted circumstellar material in stars with radiative envelopes, aiding understanding of disks and planets.

Contribution

The paper presents the CAM model, a new theoretical approach to connect stellar surface abundances with accreted material composition considering stellar mixing processes.

Findings

CAM can predict circumstellar material composition from stellar abundances.

Application to various stars shows consistency with observed accretion signatures.

The framework helps interpret the extlessboo extgreaterootnote{Note: extlessboo extgreater efers to the 'lambda Boo' phenomenon} phenomenon and disk-planet interactions.

Abstract

Protoplanetary disks, debris disks, and disrupted or evaporating planets can all feed accretion onto stars. The photospheric abundances of such stars may then reveal the composition of the accreted material. This is especially likely in B to mid-F type stars, which have radiative envelopes and hence less bulk--photosphere mixing. We present a theoretical framework (\texttt{CAM}) considering diffusion, rotation, and other stellar mixing mechanisms, to describe how the accreted material interacts with the bulk of the star. This allows the abundance pattern of the circumstellar material to be calculated from measured stellar abundances and parameters ($v_{\rm rot}$, $T_{\rm eff}$). We discuss the \lboo\ phenomenon and the application of \texttt{CAM} on stars hosting protoplanetary disks (HD~100546, HD~163296), debris disks (HD~141569, HD~21997), and evaporating planets (HD~195689/KELT-9).