Establishing binarity amongst Galactic RV Tauri stars with a disc

Abstract

This study is a contribution in comprehending the role of binarity upon late stages of stellar evolution. We determine the binary status of six Galactic RV Tauri stars, namely DY Ori, EP Lyr, HP Lyr, IRAS 17038-4815, IRAS 09144-4933 and TW Cam, which are surrounded by a dusty disc. We also place them on the HR diagram, thereby establishing their evolutionary nature. All the six Galactic RV Tauri stars included in this study are binaries with orbital periods ranging between $\sim$ 650 and 1700 days and with eccentricities between 0.2 and 0.6. The mass functions range between 0.08 to 0.55 M${}_{\odot }$ which points to an unevolved low mass companion. In the photometric time series we detect a long-term variation on the time-scale of the orbital period for IRAS 17038-4815, IRAS 09144-4933 and TW Cam. Our derived stellar luminosities obtained from a calibrated PLC relation indicates that all except DY Ori and EP Lyr, are post-AGB stars. DY Ori and EP Lyr are likely examples of the recently discovered dusty post-RGB stars. The orbital parameters strongly suggest that the evolution of these stars was interrupted by a strong phase of binary interaction during or even prior to the AGB. The observed eccentricities and long orbital periods among these stars provides a challenge to the standard theory of binary evolution.

18 pages, 19 figures, Accepted to be published in A&A

References in corpus (9)

• Keplerian discs around post-AGB stars: a common phenomenon?
• New Optical Reddening Maps of the Large and Small Magellanic Clouds
• Orbital eccentricities of binary systems with a former AGB star
• Carbon-enhanced metal-poor stars: a window on AGB nucleosynthesis and binary evolution. I. Detailed analysis of 15 binary stars with known orbital periods
• The VMC Survey. XIII. Type II Cepheids in the Large Magellanic Cloud
• Testing eccentricity pumping mechanisms to model eccentric long period sdB binaries with MESA
• Defining the instability strip of pulsating post-AGB binary stars from ASAS and NSVS photometry
• Detection of Keplerian dynamics in a disk around the post-AGB star AC Her
• The evolved circumbinary disk of AC Her: a radiative transfer, interferometric and mineralogical study

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• Resolved imaging of the AR Puppis circumbinary disk
• Physical properties of galactic RV Tauri stars from Gaia DR2 data