Spectroscopy of a sample of RV Tauri stars without IR excess

TL;DR

This study investigates the chemical compositions of 11 RV Tauri stars without IR excess using high-resolution spectra, identifying depletion patterns and binary characteristics in some stars, which enhances understanding of their evolution.

Contribution

It provides the first detailed chemical abundance analysis of RV Tauri stars without IR excess, revealing depletion patterns and binary interactions.

Findings

V457 Cyg shows chemical depletion and emission lines, indicating a circumbinary disc.

V894 Per is confirmed as an eclipsing binary, not an RV Tauri star.

High sodium overabundance suggests mass transfer in a binary system.

Abstract

We observed high-resolution optical spectra of 11 RV Tauri stars without IR excess, with the primary goal of searching for chemical depletion patterns. Using equivalent widths of absorption lines, we calculated photospheric parameters and chemical element abundances for five stars in the sample: HD 172810, V399 Cyg, AA Ari, V457 Cyg, and V894 Per. Only the abundance pattern of V457 Cyg suggests depletion. In the spectrum of this star, TiO lines are also observed in emission in addition to metal emissions. V457 Cyg is likely a binary system that was once surrounded by a circumbinary disc. In the spectrum of V894 Per, we find a set of spectral lines that appear to belong to another star, corroborating that it is an eclipsing variable rather than an RV Tauri star. The high overabundance of sodium may result from mass transfer within the binary system.