Chemical signatures of planetary systems in their host stars. Near-infrared spectroscopy of four planet-hosting wide binaries

TL;DR

This study investigates chemical abundance patterns in wide binary star systems to determine if planetary presence influences stellar chemical signatures, revealing diverse and non-universal trends.

Contribution

It provides high-resolution near-infrared spectroscopic analysis of four wide binaries with planets, highlighting varied Tc trends and suggesting multiple factors influence stellar chemical signatures.

Findings

WASP-160 A/B and WASP-127/TYC 4916-897-1 show significant Tc abundance trends.

HD 20782/HD 20781 exhibits a weaker correlation, K2-54/K2-54 B shows no trend.

Extreme Tc slopes may be more common in planet-hosting wide binaries, especially at large separations.

Abstract

An important open question in exoplanet studies is whether planets leave detectable chemical fingerprints on their host stars. While several studies have suggested possible planetary chemical signatures in planet-hosting stars, their origin remains debated because of stellar birth conditions and evolutionary effects. Wide binaries, whose components share a common formation environment, provide an ideal testbed for identifying planetary signatures. Such signatures are often characterized by differential abundance trends with condensation temperature (Tc), which traces the partitioning between gaseous and rocky planetary material. We investigate whether these trends are associated with planetary architectures in wide binaries. We obtained high-resolution NIR spectra of four planet-hosting wide binaries. We measured abundances for both components and analyzed differential abundances in each system. We also compiled literature measurements for planet-hosting and non-hosting wide binaries and compared their Tc trends. WASP-160 A/B and WASP-127/TYC 4916-897-1 exhibit significant abundance trends with Tc, while HD 20782/HD 20781 shows a weaker correlation and K2-54/K2-54 B is consistent with a flat relation. The trends are diverse, including both volatile- and refractory-enhanced patterns in planet-hosting stars. Literature comparisons indicate that extreme Tc slopes may occur more frequently among planet-hosting wide binaries, particularly at large separations, although the statistics remain limited by sample size and definition. Our results indicate that chemical signatures in planet-hosting wide binaries are not universal but vary across systems. While planetary architectures may be associated with some host-star abundance patterns, multiple processes are likely to contribute. Larger samples are essential for disentangling planetary signatures from stellar and binary effects.