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تسجيل مستخدم جديدThe HI Kinematics of NGC 4013: a Steep and Radially Shallowing Extra-planar Rotational Lag
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NGC 4013 is a distinctly warped galaxy with evidence of disk-halo activity. Through deep HI observations and modeling we confirm that the HI disk is thin (central exponential scale height of with an upper limit of 4 or 280 pc), but flaring. We detect a vertical gradient in rotation velocity (lag), which shallows radially from a value of -35 +7/-28 km/s/kpc at 1.4 (5.8 kpc), to a value of zero near R_25 (11.2 kpc). Over much of this radial range, the lag is relatively steep. Both the steepness and the radial shallowing are consistent with recent determinations for a number of edge-ons, which have been difficult to explain. We briefly consider the lag measured in NGC 4013 in the context of this larger sample and theoretical models, further illuminating disk-halo flows.
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