Astron. Astrophys. 357, L61-L64 (2000)

Letter to the Editor

T Tauri stars microjets resolved by adaptive optics  ^*

C. Dougados ^1,3, S. Cabrit ², C. Lavalley ¹ and F. Ménard <sup>3

1</sup> Laboratoire d'Astrophysique, Observatoire de Grenoble, CNRS/UJF UMR 5571, B.P. 53, 38041, Grenoble Cedex 9, France
² Observatoire de Paris, DEMIRM, URA 336 du CNRS, 61 Avenue de l'Observatoire, 75014 Paris, France
³ Canada-France-Hawaii Telescope Corporation, PO Box 1597, Kamuela HI 96743,USA

Received 30 March 2000 / Accepted 17 April 2000

Abstract

Using adaptive optics techniques, we have obtained the first [O I ] and [S II ] images at 0.1" ( 15 AU) resolution of the jets in CW Tau, DG Tau and RW Aur. In all three jets, the emission is dominated by knots and is resolved transversally down to 56 AU with similar inner jet widths of 0.2-0.25". The RW Aur and CW Tau jets are straight, their FWHM slowly increasing with distance with opening angles of 3-4^o. In contrast, the DG Tau jet seems to be precessing and its FWHM reaches 1.3" at 335 AU, where contamination by strong bow-shock wings most likely occurs. The widths of the CW Tau and RW Aur jets are strikingly similar to those measured in HH 30 and HL Tau, two active TTs, on similar spatial scales. The derived upper limit on the density collimation size scale of 50 AU and intrinsic jet widths of 30 AU over the central 100 AU are in quantitative agreement with predictions from current MHD wind models. In DG Tau we confirm the bow-shaped morphology and detect a high proper motion (194 km s^-1) for the knot located at 3.3". The properties of this knot strongly support the model of internal working surfaces produced by variable ejection.

Key words: stars: pre-main sequence stars: mass-loss stars: individual: CW Tau, DG Tau, RW Aur stars: emission-line, Be ISM: individual objects: HH 158, HH 220, HH 229 ISM: jets and outflows

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

Send offprint requests to: dougados@obs.ujf-grenoble.fr

© European Southern Observatory (ESO) 2000

Online publication: June 5, 2000

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