On Binary Channels to Anomalous Cepheids

Abstract

Anomalous Cepheids are a rather rare family of pulsating variables preferably found in dwarf galaxies. Attempts to model these variable stars via single-star evolution scenarios still leave space for improvements to better grasp their origin. Focusing on the LMC with its rich population of Anomalous Cepheids to compare against we probe the role binary stars might play to understand the nature of Anomalous Cepheids. The evolution of donors and accretors undergoing Case-B mass transfer along the first red-giant branch as well as merger-like models were calculated. First results show that in binary scenarios a larger range of star masses and metallicities up to Z < 0.008, higher than deemed possible hitherto, enter and pass through the instability strip. If binary stars play a role in Anomalous Cepheid populations, mass donors, mass accretors, or even mergers are potential candidates to counteract constraints imposed by the single-star approach.

11 pages, 12 figures, accepted for publication in MNRAS

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• A DECam View of the Diffuse Dwarf Galaxy Crater II: The Colour-Magnitude Diagram
• Searching for Anomalies in the ZTF Catalog of Periodic Variable Stars
• OGLE-GAL-ACEP-091 -- The First Known Multi-Mode Anomalous Cepheid
• Type II and anomalous Cepheids in the Kepler K2 mission
• The VMC Survey -- LIV. Anomalous Cepheids in the Magellanic Clouds Period-Luminosity relations in the near-infrared bands
• Asteroseismic Imprints of Mass Transfer in Binary Stars: Probing the Interiors of Donors and Accretors with Gravity and Acoustic Modes