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Recent results of long-slit spectroscopy of the forbidden lines of the outflow in the young star DG Tau [7] suggest that its wind is well collimated very close to it, leading to the formation of its jet. The analysis of the width of stellar jets, on the other hand, seems to indicate that the collimation of the jets takes place at larger scales [5].
In other to understand this discrepancy, we are studying by means of a two dimensional hydrodynamical code [1][3], the collimation driven by the interaction of the stellar wind with the surrounding density structure left by the star formation process [8][9].
We have found in our adiabatic outflow simulations (using physical parameters similar to those for the HH 34 bipolar stellar jet [2]) that a spherical wind is well collimated near the source resembling a de Laval Nozzle [4][6].
ANC research is supported by NSF grant AST-91-14888. \vspace*{0.3cm}
References
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[5] Mundt, R., Ray, T.P., \& Raga, A.C. 1991, A\&A 252, 740.
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[7] Solf, J., \& B\"ohm, K.H. 1993, ApJL (in press).
[8] Terebey, S., Shu, F.H., \& Cassen, P. 1984, ApJ 286, 529.
[9] Yorke, H.W., Bodenheimer, P., \& Laughlin, G. 1993, ApJ (in press).
