We carried out optical high-resolution spectroscopy of T Tauri stars using the Subaru Telescope .
Using archive data of the Keck Telescope and the Very Large Telescope , we detected forbidden lines of [ S II ] at 4069 Å , in addition to those of [ O I ] at 5577 Å and 6300 Å , for 13 T Tauri stars .
We consider that low-velocity components of these forbidden lines emanate from the wind associated with T Tauri stars .
Using two flux ratios of the three lines , we simultaneously determined the hydrogen density and temperature of the winds .
The winds of T Tauri stars have the hydrogen density of 2.5 \times 10 ^ { 6 } cm ^ { -3 } -2.5 \times 10 ^ { 9 } cm ^ { -3 } and the temperature of 10800 K – 18000 K. The mass loss rates by the wind are estimated to lie in the range from 2.0 \times 10 ^ { -10 } M _ { \odot } yr ^ { -1 } to 1.4 \times 10 ^ { -9 } M _ { \odot } yr ^ { -1 } .
The mass loss rates are found to increase with increasing mass accretion rates .
The ratio of the mass loss rate to the mass accretion rate is 0.001 – 0.1 for the classical T Tauri stars and 0.1 – 1 for the transitional disk objects .