|Water emission in the shocked regions at the tips of converging filaments
|nguyen luong, q.
|The scenario of colliding flows driving molecular cloud formation (Vazquez-Semadeni et al. 2011; Hennebelle et al. 2008; Heitsch et al. 2008) is currently the most promising to explain the short star formation timescales and filamentary geometries observed (e.g. Hartmann et al. 2001). In this framework, molecular clouds are never in equilibrium state, as part of the cloud collapses while most of it disperses. High-density seeds result from the compression and gathering of material at stagnation points. Therefore, the structure and kinematics of these high-density clumps-cores and their surrounding low-density clouds may still reflect such a process. Especially, at the stagnation points (tips of the converging filaments), strong thermal fragmentation amplifies, shocks can emerge to shed the kinetic and thermal energy away from different gas flows (Heitsch et al. 2008). At the meeting layer between the converging flows, the reversed shocks will become an incubator for the cores to self-gravitate and collapse to form stars (Gong et al. 2011). Thus, evidences of converging flows can be found through a combined observations of velocity gradient-jumps toward the center, presence of protostars and signature of shock layers. We propose here to image water emission arising from the high-density ridges hosting the high-mass protostars W43-MM1 and MM2, which we have detected extended SiO emission, a hint to converging flows. Water emission is an ideal tracer to distinguish coherent kinematic patterns of converging-flows shock from the abrupt pattern of the outflow or hot core; to trace the velocity field of the converging flows from the outskirt to SiO knots to better constrain the pre- and post-shock conditions in W43, the connecting to the pre-converging low-density cloud; to determine the layer where shock terminate and leave only the fragmented dense cores hosting high-mass protostars.
|Herschel was launched on 14 May 2009! It is the fourth 'cornerstone' mission in the ESA science programme. With a 3.5 m Cassegrain telescope it is the largest space telescope ever launched. It is performing photometry and spectroscopy in approximately the 55-671 µm range, bridging the gap between earlier infrared space missions and groundbased facilities.
|Publisher And Registrant
|European Space Agency
|European Space Agency, 2013, OT2_qnguyenl_1, SPG v14.1.0. https://doi.org/10.5270/esa-5zbhzex