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3-dimensional sketch of the massive protostar NGC7538-IRS1.

Submitter: Gabriele Surcis
Description: NGC7538-IRS1 is the brightest protostar in the massive star-forming region NGC7538 located in the Perseus arm of our Galaxy at a distance of 2.65 kpc. This protostar has a large-scale molecular bipolar outflow (indicated by the two cones; Kameya et al. 1989,ApJ, 339, 222) and a molecular torus rotating clockwise (grey donut; Klaaseen et al. 2009, ApJ, 703, 1308). Several maser species have been detected towards NGC7538-IRS1 (OH, H2O, and CH3OH) that are consistent with the torus-outflow scenario. In particular the methanol masers (red triangles) are tracing the interface between the infall and the torus, and the water masers (blue circles) are instead related to the blue-shifted part of the outflow (Surcis et al. 2011, A&A, 533, 47). Here the OH masers are also shown (green squares, Hutawarakorn & Cohen 2003, MNRAS, 345, 175), that are thought to be associated with the gas surrounding the torus. From EVN polarization observations of the 6.7 GHz CH3OH masers we have determined the orientation of the magnetic field on the top surface of the torus, which has a counterclockwise direction. For more details read Surcis et al. 2011, A&A, 533, 37 or http://hss.ulb.uni-bonn.de/2011/2642/2642.htm .
Copyright: Surcis Gabriele
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