A deep long-slit spectroscopic study of the two bipolar outflows from the T Tauri binary system

We present results of a new deep, high-resolution, long-slit spectroscopic study of the extended nebular line emission around the young binary T Tauri . The deduced position-velocity diagrams of the [O I], [N II], and [S II] l ines have been used to investigate in great detail the complex geometric an d kinematic structure of the mass outflows from the stellar binary componen ts T Tau N and T Tau S. A large number of distinct extended outflow compone nts, each of them characterized by its specific spatio-kinematic properties , has been identified. In addition to the brighter components (A, B, C, D, E, and F) already described in detail by Bohm & Solf, we have detected seve ral much fainter components (G, H, I, J, K, and L), some of them extending up to similar to 40 " from the central binary. The new data confirm the exi stence of two separate bipolar outflow systems associated with the binary: one of them oriented near the east-west direction and probably originating from the visible binary component T Tau N, the other one oriented near the north-south direction and probably originating from the infrared binary com ponent T Tau S. In the east-west outflow, so far considered to be represent ed only by blueshifted components (B, F, and H) west of T Tau N, we have de tected for the first time an indication for a redshifted faint counterjet ( G) east of T Tan, corresponding to the known HH 155 jet (H). In the north-s outh outflow, so far considered to be represented only by two components (C and D) near the central source (less than or equal to 3 "), two additional , rather faint components (I and J) have been detected, which are located f arther out (8 "-15 ") on opposite sides of the source. Both faint component s present rather low velocities of opposite sign but rather large velocity dispersions of about 75-100 km s(-1) (FWHM). Using a biconical model for th e outflow geometry, we have derived an inclination angle of 79 degrees with respect to the line of sight for the bipolar axis and deduced typical velo cities of similar to 91 and similar to 280 km s(-1) in the faint outer regi ons (I and J) and the bright inner regions (C and D) of the north-south out flow, respectively. We have compared the kinematic state (mean radial veloc ity and velocity dispersion) of the "hot" (partially) ionized gas of the ou tflows from the binary T Tau deduced from our forbidden line observations w ith that of the "warm" molecular gas determined from the v = 1-0 S(1) line of H-2 observations by T. M. Herbst and coworkers. In principal, the [S II] and H-2 emission regions refer to very different spatial regions of the ou tflows, and hence the kinematic states of the two regions do not have to be coupled to each other. In particular, it is expected that the velocity dis persion derived from the [S II] lines is much larger than that from the H-2 lines. These expectations are generally fulfilled by the observations, exc ept for the "core" region of Burnham's nebula (component E) where the veloc ity dispersions of both the forbidden and H-2 lines are approximately the s ame. These findings as well as other enigmatic properties of Burnham's nebu la reported earlier are not yet understood.