Strong dust processing in circumstellar discs around 6 RV Tauri stars. Are dusty RV Tauri stars all binaries?

TL;DR

This study analyzes the spectral energy distributions of seven RV Tauri stars, revealing that most have circumstellar dust in discs likely formed in binary systems, with implications for their structure and evolution.

Contribution

It provides new submillimetre measurements and suggests that dusty RV Tauri stars predominantly host circumstellar discs formed through binary interactions.

Findings

Six of seven stars show IR excess indicating large grain dust in discs.

Discs are likely Keplerian and formed in binary systems.

Dust near sublimation temperature with low outflow velocities.

Abstract

We present extended Spectral Energy Distributions (SEDs) of seven classical RV Tauri stars, using newly obtained submillimetre continuum measurements and Geneva optical photometry supplemented with literature data. The broad-band SEDs show a large IR excess with a black-body slope at long wavelengths in six of the seven stars, R Sct being the noticeable exception. This long wavelength slope is best explained assuming the presence of a dust component of large grains in the circumstellar material. We show that the most likely distribution of the circumstellar dust around the six systems is that the dust resides in a disc. Moreover, very small outflow velocities are needed to explain the presence of dust near the sublimation temperature and we speculate that the discs are Keplerian. The structure and evolution of these compact discs are as yet not understood but a likely prerequisite for their formation is that the dusty RV Tauri stars are binaries.