The Tc trend in the Zetta Reticuli system: N spectra - N trends

TL;DR

This study re-evaluates the chemical abundance trends with condensation temperature in the Zetta Reticuli system, highlighting the influence of spectral data variability and cautioning against overinterpreting such trends as signatures of planet formation.

Contribution

It provides a comprehensive analysis using a larger spectral dataset, demonstrating that Tc trends can be affected by nonphysical factors and are not always indicative of planetary processes.

Findings

Tc trends depend on the individual spectra used.

Nonphysical factors can influence observed Tc trends.

Re-evaluation questions previous interpretations of planet formation signatures.

Abstract

It is suggested that the chemical abundance trend with the condensation temperature, Tc , can be a signature of rocky planet formation or accretion. Recently, a strong Tc trend was reported in the Zetta Reticuli binary system (Saffe et al., 2016), where ${\zeta}$2 Ret Ret shows a deficit of refractory elements relative to its companion (${\zeta}$1 Ret). This depletion was explained by the presence of a debris disk around ${\zeta}$2 Ret. Later, Adibekyan et al. (2016b) confirmed the significance of the trend, however, casted doubts on the interpretation proposed. Using three individual highest quality spectra for each star, they found that the Tc trends depend on the individual spectra (three spectra of each star were used) used in the analaysis. In the current work we re-evaluated the presence and variability of the Tc trend in this system using a larger number of individual spectra. In total, 62 spectra of ${\zeta}$2 Ret and 31 spectra of ${\zeta}$1 Ret was used. Our results confirm the word of caution issued by Adibekyan et al. (2016b) that nonphysical factors can be at the root of the T c trends for the cases of individual spectra.