Ionisation impact of high-mass stars on interstellar filaments. A Herschel study of the RCW 36 bipolar nebula in Vela C
Hill, T.; White, G. J.; André, Ph.; Rygl, K. L. J.; Schneider, N.; Tremblin, P.; Zavagno, A.; Didelon, P.; Di Francesco, J.; Elia, D.; Motte, F.; Pezzuto, S.; Spinoglio, L.; Ward-Thompson, D.; Hennemann, M.; Nguyen Luong, Q.; Minier, V.; Giannini, T.; Audit, E.; Deharveng, L.; Lo, N.; Cunningham, M.
France, Chile, United Kingdom, Australia, Canada, Italy
Abstract
Context. Ionising stars reshape their original molecular cloud and impact star formation, leading to spectacular morphologies such as bipolar nebulae around H ii regions. Molecular clouds are structured in filaments where stars principally form, as revealed by the Herschel space observatory. The prominent southern hemisphere H ii region, RCW 36, is one of these bipolar nebulae.
Aims: We study the physical connection between the filamentary structures of the Vela C molecular cloud and the bipolar morphology of RCW 36, providing an in-depth view of the interplay occurring between ionisation and interstellar structures (bright-rims and pillars) around an H ii region.
Methods: We have compared Herschel observations in five far-infrared and submillimetre filters with the PACS and SPIRE imagers, to dedicated numerical simulations and molecular line mapping.
Results: Our results suggest that the RCW 36 bipolar morphology is a natural evolution of its filamentary beginnings under the impact of ionisation.
Conclusions: Such results demonstrate that, filamentary structures can be the location of very dynamical phenomena inducing the formation of dense clumps at the edge of H ii regions. Moreover, these results could apply to better understanding the bipolar nebulae as a consequence of the expansion of an H ii region within a molecular ridge or an interstellar filament.