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Astron. Astrophys. 356, L41-L44 (2000)


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Letter to the Editor

DG Tau: A shocking jet *

C. Lavalley-Fouquet 1, S. Cabrit 2 and C. Dougados 1,3

1 Laboratoire d'Astrophysique de l'Observatoire de Grenoble, B.P. 53, 38041 Grenoble Cedex, France
2 Observatoire de Paris, DEMIRM, UMR 8540 du CNRS, 61 Avenue de l'Observatoire, 75014 Paris, France
3 Canada-France-Hawaii Telescope Corporation, PO Box 1597, Kamuela HI 96743, USA

Received 15 February 2000 / Accepted 26 February 2000

Abstract

We present spectro-imaging observations of DG Tau at 0.5" resolution obtained with OASIS in [O I ][FORMULA]6300, H[FORMULA], [N II ][FORMULA]6583, and [S II ][FORMULA]6716,6731. The fast jet core appears wiggling and surrounded by a slower moving flow or cavity. Line ratios are compared with available predictions for heating mechanisms in T Tauri jets (shocks, ambipolar diffusion, turbulent mixing-layers). Shocks with speeds 50-100 km s-1 increasing with flow velocity, and preshock densities [FORMULA]-[FORMULA] cm-3 decreasing away from the star, are best able to reproduce the high level of excitation for velocities [FORMULA] 100 km s-1.

Key words: shock waves – stars: individual: – stars: pre-main sequence – ISM: jets and outflows

* Based on observations collected at the Canada-France-Hawaii Telescope (CFHT), operated by the National Research Council of Canada, the Centre National de la Recherche Scientifique, and University of Hawaii.

Send offprint requests to: sylvie.cabrit@obspm.fr

© European Southern Observatory (ESO) 2000

Online publication: April 10, 2000

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