LONG-SLIT SPECTROSCOPY OF PARSEC-SCALE JETS FROM DG TAURI

We present observational results from optical long-slit spectroscopy of parsec-scale jets of DG Tau. From HR 158 and HH 702, the optical emission lines of H alpha, [O I] lambda lambda 6300, 6363, [N II] lambda lambda 6548, 6584, and [S II] lambda lambda 6716, 6731 are obtained. The kinematics and physical properties (i.e., electron density, electron temperature, ionization fraction, and mass-loss rate) are investigated along the blueshifted jet up to 650 '' distance from the source. For HH 158, the radial velocity ranges from -50 to -250 km s(-1). The proper motion of the knots is 0 ''.196 - 0 ''.272 yr(-1). The electron density is similar to 10(4) cm(-3) close to the star, and decreases to similar to 10(2) cm(-3) at 14 '' away from the star. Ionization fraction indicates that the gas is almost neutral in the vicinity of the source. It increases up to over 0.4 along the distance. HH 702 is located at 650 '' from the source. It shows similar to -80 km s(-1) in the radial velocity. Its line ratios are similar to those at knot C of HH 158. The mass-loss rate is estimated to be about similar to 10(-7) M-circle dot yr(-1), which is similar to values obtained from previous studies.