Slawa Kabanovic
I. Physikalisches Institut, Universität zu Köln
Highlights of the SOFIA Legacy Program FEEDBACK and Future Perspectives on Orion A
Slawa Kabanovic, Nicola Schneider and the Feedback consortium
During the FEEDBACK legacy survey, 11 high-mass star-forming regions were observed using the [CII] 158 and [OI] 63 micron lines with the upGREAT receiver on SOFIA. The program has been completed up to approximately 80%. We here present the scientific highlights that resulted in so far 14 publications including a Nature Astronomy and a Science Advances article and give a status report on our ongoing work in Orion A. One significant focus of FEEDBACK was the exploration of galactic HII region bubbles. Expanding [CII] shells were identified in all sources, and potential driving mechanisms were assessed. Our findings indicate that, in the majority of cases (e.g. RCW120, RCW36, NGC7538), the high-velocity expansion is attributed to the stellar wind from massive stars (Luisi et al. 2021, Bonne et al. 2022, Beuther et al. 2022). Recently, we uncovered signs of cloud destruction due to stellar winds and radiation, quantifying this phenomenon using [CII] in the RCW79 region (Bonne et al. 2023). Utilizing a multi-layer radiative transfer model for CO and [CII] emission, coupled with HI self-absorption (HISA) studies, we investigated the RCW 120 bubble (Kabanovic et al. 2022). Our study detected significant amounts of cold C+ linked to an extensive HI envelope and revealed that the related molecular cloud exhibits a flattened structure likely originating from a residual filament. In Cygnus X, we unveiled the highly dynamic interaction of CO-dark gas in the form of atomic flows with a small molecular fraction (Schneider et al. 2023), using [CII], CO emission and HISA. The cloud formation timescale is only ~1 Myr, consistent with recent simulations of fast, colliding HI flows (e.g., Dobbs et al. 2020). As part of the Orion Legacy project (PI S. Kabanovic), multiple long-time integrations across Orion A were performed, successfully detecting weak [13CII] transition lines. These observations enable the first determination of the local [12CII]/[13CII] abundance ratio and possible fractionation effects directly in different physical conditions in Orion A, such as NGC 1977, M43, and M42. Beuther H., et al. 2022 A&A, 659, 77 Bonne L., et al. 2022 ApJ, 935, 171 Bonne L., et al. 2023, A&A Letters, 679, 5 Dobbs C., et al. 2020, MNRAS Lett. 496(1), 1 Kabanovic S., et al. 2022, A&A, 659, 36 Luisi M., et al. 2021 Science Advances, 9 Apr 2021, Vol. 7 Schneider N., et al., Nature Astronomy, vol. 7, p. 546
