The inflow motion is measured. Figure 1.15 shows the isovelocity contours measured by the CO observation (Ohashi et al 1996). It should be noticed that the isovelocity lines run parallelly to the major axis. The north-eastern side shows a red-shift and the south-western side shows a blue-shift. Considering the configuration of the gas disk shown in Fig.1.14 (right), this pattern of isovelocity contours indicates not outflow but inflow. That is, the north-east side is a near side of the disk and the south-west side is a far side. Since a red-shifted motion is observed in the near side and a blue-shifted motion is observed in the far side, it should be concluded that the gas disk of the L1551 IRS5 is now infalling.
Kohji Tomisaka 2012-10-03