Detailed elemental abundances of binary stars: Searching for signatures of planet formation and atomic diffusion

TL;DR

This study investigates whether elemental abundance patterns in binary stars reveal signatures of planet formation or atomic diffusion, finding subtle differences that may be influenced by these processes but not directly by planet presence.

Contribution

The paper provides high-precision differential abundance analysis of binary stars, exploring the effects of atomic diffusion and planet formation on stellar chemical signatures.

Findings

Subtle abundance differences observed in 4 of 7 binary systems.

No clear correlation between abundance differences and planet occurrence.

Possible influence of atomic diffusion on observed abundance offsets.

Abstract

Binary star systems are assumed to be co-natal and coeval, thus to have identical chemical composition. In this work we aim to test the hypothesis that there is a connection between observed element abundance patterns and the formation of planets using binary stars. Moreover, we also want to test how atomic diffusion might influence the observed abundance patterns. We conduct a strictly line-by-line differential chemical abundance analysis of 7 binary systems. Stellar atmospheric parameters and elemental abundances are obtained with extremely high precision (< 3.5%) using the high quality spectra from VLT/UVES and Keck/HIRES. We find that 4 of 7 binary systems show subtle abundance differences (0.01 - 0.03 dex) without clear correlations with the condensation temperature, including two planet-hosting pairs. The other 3 binary systems exhibit similar degree of abundance differences correlating with the condensation temperature. We do not find any clear relation between the abundance differences and the occurrence of known planets in our systems. Instead, the overall abundance offsets observed in the binary systems (4 of 7) could be due to the effects of atomic diffusion. Although giant planet formation does not necessarily imprint chemical signatures onto the host star, the differences in the observed abundance trends with condensation temperature, on the other hand, are likely associated with diverse histories of planet formation (e.g., formation location). Furthermore, we find a weak correlation between abundance differences and binary separation, which may provide a new constraint on the formation of binary systems.