The Invisible Monster Has Two Faces: Observations of Epsilon Aurigae with the Herschel Space Observatory

TL;DR

This study uses Herschel Space Observatory data to analyze the dust disk around Epsilon Aurigae, revealing a cool, low gas-to-dust ratio disk and clarifying previous radio detection ambiguities.

Contribution

First Herschel observations of Epsilon Aurigae's dust disk, providing detailed spectral energy distribution and insights into disk composition and background contamination.

Findings

Disk is consistent with a cool 550 K model

Lack of molecular emission indicates low gas-to-dust ratio

Radio detection likely contaminated by background emission

Abstract

We present Herschel Space Observatory photometric observations of the unique, long-period eclipsing binary star Epsilon Aurigae. Its extended spectral energy distribution is consistent with our previously published cool (550 K) dust disk model. We also present an archival infrared spectral energy distribution of the side of the disk facing the bright F-type star in the binary, which is consistent with a warmer (1150 K) disk model. The lack of strong molecular emission features in the Herschel bands suggests that the disk has a low gas-to-dust ratio. The spectral energy distribution and Herschel images imply that the 250 GHz radio detection reported by Altenhoff et al. is likely contaminated by infrared-bright, extended background emission associated with a nearby nebular region and should be considered an upper limit to the true flux density of Epsilon Aur.