An Infrared Nebula Associated with Delta Cephei: Evidence of Mass Loss?

TL;DR

This paper reports the discovery of an infrared nebula around delta Cephei, providing evidence that the star may be losing mass through stellar winds, with implications for understanding Cepheid evolution.

Contribution

It presents the first detection of a large-scale infrared nebula around delta Cephei, indicating mass loss and bow shock formation, a novel observation for Cepheid variables.

Findings

Infrared nebula detected around delta Cephei at multiple wavelengths.

Nebula features suggest mass loss rate of approximately 5x10^-9 to 6x10^-8 solar masses per year.

Presence of bow shock aligned with star's proper motion.

Abstract

We present the discovery of an infrared nebula around the Cepheid prototype delta Cephei and its hot companion HD 213307. Large scale (~2.1x10^4 AU) nebulosity is detected at 5.8, 8.0, 24 and 70 um. Surrounding the two stars, the 5.8 and 8.0 um emission is largely attributable to Polycyclic Aromatic Hydrocarbon (PAH) emission swept from the ISM by a wind originating from delta Cephei and/or its companion. Stochastically heated small dust grains are the most likely source of the 24 and 70 um extended emission. The 70 um emission, in particular, resembles a bow shock aligned in the direction of the proper motion of delta Cephei. This discovery supports the hypothesis that delta Cephei may be currently losing mass, at a rate in the range ~ 5x10^-9 to 6x10^-8 Mo/yr.