Contributed Talk - Splinter SOFIA

Tuesday, 12 September 2023, 15:45   (H 3006)

FEEDBACK observations of RCW79

E. Keilmann, L. Bonne, S. Kabanovic, N. Schneider and the FEEDBACK team
I. Physikalisches Institut, Universität zu Köln; SOFIA Science Center, USRA, NASA Ames Research Center

We here present recent results of large-scale mapping of the [CII] 158μm line and other tracers of photodissociated (PDR) gas, in the RCW79 HII region, obtained with the SOFIA legacy program FEEDBACK. Firstly, blue- and red-shifted high-velocity gas (up to 25 km/s relative to the bulk emission of the molecular cloud) is detected in [CII] that arises in part from a fragmented shell, similar to what was found before for other HII region bubbles. However, we also detect high-velocity gas ablated from the edge of the turbulent molecular cloud into the surrounding interstellar medium through low-pressure holes or chimneys. The calculated mass ejection rates lead to short erosion timescales of less than 5 Myr. This finding provides direct observational evidence of rapid molecular cloud dispersal by stellar feedback (Bonne et al., submitted to ApJL). Secondly, we observed for the first time in the south-eastern ring of RCW79 a compact HII bubble that is mostly filled with ionized carbon, and not only expanding shells. The expansion velocity is much lower (around 5 km/s) and we assume that we observe a very early stage of HII region expansion (Keilmann et al., in prep.). Thirdly, we use SOFIA [CII] 158μm, [OI] 63μm, [CI] 490 GHz observations and CO 3-2 line data from APEX to perform PDR modelling to derive the excitation conditions in the atomic and molecular gas (Keilmann et al., in prep.).