The Connection Between Pulsation, Mass Loss and Circumstellar Shells in Classical Cepheids

TL;DR

This paper investigates the link between pulsation, mass loss, and circumstellar shells in Cepheids, using models and observations to explain IR excess and the Cepheid mass discrepancy.

Contribution

It introduces a modified wind model for Cepheids and tests for circumstellar envelopes in LMC Cepheids using IR data, linking mass loss to the mass discrepancy.

Findings

IR excess is common in LMC Cepheids

Mass loss can explain part of the mass discrepancy

IR fluxes indicate presence of CSEs in Cepheids

Abstract

Recent observations of Cepheids using infrared interferometry and Spitzer photometry have detected the presence of circumstellar envelopes (CSE) of dust and it has been hypothesized that the CSE's are due to dust forming in a Cepheid wind. Here we use a modified Castor, Abbott & Klein formalism to produce a Cepheid wind, and this is used to estimate the contribution of mass loss to the Cepheid mass discrepancy Furthermore, we test the OGLE-III Classical Cepheids using the IR fluxes from the SAGE survey to determine if Large Magellanic Cloud Cepheids have CSE's. It is found that IR excess is a common phenomenon for LMC Cepheids and that the resulting mass-loss rates can explain at least a fraction of the Cepheid mass discrepancy, depending on the assumed dust-to-gas ratio in the wind.