SOFIA FEEDBACK Survey: Exploring the Dynamics of the Stellar Wind Driven Shell of RCW 49
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Maitraiyee Tiwari
University of Maryland
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The SOFIA legacy project FEEDBACK aims to quantify the radiative and mechanical feedback from stars in the ISM. For this, we plan to map the C+ ([CII]) emission towards 11 massive star-forming regions in our Galaxy. The fine structure line of [CII] is one of the most dominant coolants in the ISM, yielding the radiative energy injection. It also provides the kinematics of the gas exposed to stellar winds, measuring the mechanical energy input. We presented one of our first results by unveiling the stellar wind driven shell of the luminous massive star-forming region of RCW 49 using SOFIA FEEDBACK observations of the [C II] 158 µm line. The complementary dataset of the 12CO and 13CO 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 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.

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