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