Protostars and Planets VI, Heidelberg, July 15-20, 2013
Dissociative shocks in the inner 100 AU of low-mass protostars
Kristensen, L.E. (Harvard-Smithsonian Center for Astrophysics)
Even for low-mass protostars (Lbol < 100 Lsun) star formation is a violent process. The inner dense envelope is illuminated by X-rays and UV radiation from the accreting protostar, while the same inner envelope is exposed to the protostellar jet and wind, both causing shocks in the dense gas. Thus, the chemical and physical conditions along the outflow cavities are significantly different from the conditions in the bulk of the cold envelope. The hot gas (T > 500 K) remains largely uncharacterized in spite of the fact that it is observed toward nearly every low-mass protostar with Herschel-PACS.
Recent observations obtained with Herschel-HIFI as part of the \"Water in star-forming regions with Herschel\" program (WISH) will be presented. The velocity-resolved line profiles of water and related hydrides (OH+, OH, CH+) point to a physical origin of the hot gas to be in dissociative shocks located in the inner few 100 AU of the protostar. Complementary SubMillimeter Array (SMA) data shed further light on both the spatial location and excitation conditions in these shocks. Finally, ALMA Science Verification data show how and where gas is put in motion on small scales (~ 100 AU). All of these observations pave the way for future studies of shocks and entrainment in low-mass protostars.
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