SOFIA FEEDBACK survey: exploring the dynamics of the stellar wind driven shell of RCW 49

TL;DR

This study uses SOFIA FEEDBACK and APEX observations to analyze the expanding stellar wind-driven shell of RCW 49, revealing its morphology, dynamics, and potential re-acceleration sources in a complex star-forming region.

Contribution

First detailed multi-wavelength analysis of RCW 49's shell dynamics using SOFIA FEEDBACK data, identifying re-acceleration mechanisms and shell morphology.

Findings

Shell radius ~6 pc, expanding at 13 km/s.

Shell's expansion lifetime ~0.27 Myr.

Wolf-Rayet star WR20a likely re-accelerates the shell.

Abstract

We unveil the stellar wind driven shell of the luminous massive star-forming region of RCW 49 using SOFIA FEEDBACK observations of the [CII] 158 $\mu$m line. The complementary dataset of the $^{12}$CO and $^{13}$CO J = 3 - 2 transitions is observed by the APEX telescope and probes the dense gas toward RCW 49. Using the spatial and spectral resolution provided by the SOFIA and APEX telescopes, we disentangle the shell from a complex set of individual components of gas centered around RCW 49. We find that the shell of radius ~ 6 pc is expanding at a velocity of 13 km s$^{-1}$ toward the observer. Comparing our observed data with the ancillary data at X-Ray, infrared, sub-millimeter and radio wavelengths, we investigate the morphology of the region. The shell has a well defined eastern arc, while the western side is blown open and is venting plasma further into the west. Though the stellar cluster, which is ~ 2 Myr old gave rise to the shell, it only gained momentum relatively recently as we calculate the shell's expansion lifetime ~ 0.27 Myr, making the Wolf-Rayet star WR20a a likely candidate responsible for the shell's re-acceleration.