EVLA observations of the nebula around G79.29+0.46

TL;DR

This study uses EVLA radio observations to analyze the morphology and dust components of the nebula around G79.29+0.46, revealing nested shells, dust populations, and interactions with the interstellar medium, informing stellar evolution models.

Contribution

First detailed comparison of radio and mid-IR images of G79.29+0.46's nebula, identifying dust populations and shell ejection timescales.

Findings

Detection of a second dust shell at 24 and 70 micrometers.

Identification of two distinct dust populations with different temperatures.

Evidence of interaction between the nebula and surrounding interstellar medium.

Abstract

We have observed the radio nebula surrounding the Galactic LBV candidate G79.29+0.46 with the EVLA at 6 cm. These new radio observations allow a morphological comparison between the radio emission, which traces the ionized gas component, and the mid-IR emission, a tracer of the dust component. The IRAC (8 \mu m) and MIPS (24 \mu m and 70 \mu m) images have been reprocessed and compared with the EVLA map. We confirm the presence of a second shell at 24 \mu m and also provide evidence for its detection at 70 \mu m. The differences between the spatial morphology of the radio and mid-IR maps indicate the existence of two dust populations, the cooler one emitting mostly at longer wavelengths. Analysis of the two dusty, nested shells have provided us with an estimate of the characteristic timescales for shell ejection, providing important constraints for stellar evolutionary models. Finer details of the ionized gas distribution can be appreciated thanks to the improved quality of the new 6 cm image, most notably the highly structured texture of the nebula. Evidence of interaction between the nebula and the surrounding interstellar medium can be seen in the radio map, including brighter features that delineate regions where the shell structure is locally modified. In particular, the brighter filaments in the south-west region appear to frame the shocked southwestern clump reported from CO observations.