EDP Sciences
Free access
Volume 453, Number 3, July III 2006
Page(s) 785 - 796
Section Astrophysical processes
DOI http://dx.doi.org/10.1051/0004-6361:20054231

A&A 453, 785-796 (2006)
DOI: 10.1051/0004-6361:20054231

Which jet launching mechanism(s) in T Tauri stars?

J. Ferreira1, C. Dougados1 and S. Cabrit2

1  Laboratoire d'Astrophysique de Grenoble, BP 53, 38041 Grenoble Cedex, France
    e-mail: Jonathan.Ferreira@obs.ujf-grenoble.fr
2  Observatoire de Paris, LERMA, UMR 8112 du CNRS, 61 avenue de l'Observatoire, 75014 Paris, France

(Received 20 September 2005 / Accepted 24 March 2006)

Aims.We examine whether ejection phenomena from accreting T Tauri stars can be described by only one type of self-collimated jet model.
Methods.We present analytical kinematic predictions valid soon after the Alfvén surface for all types of steady magnetically self-confined jets.
Results.We show that extended disc winds, X-winds, and stellar winds occupy distinct regions in the poloidal speed vs. specific angular momentum plane. Comparisons with current observations of T Tauri jets yield quantitative constraints on the range of launching radii, magnetic lever arms, and specific energy input in disc and stellar winds. Implications on the origin of jet asymmetries and disc magnetic fields are outlined.
Conclusions.We argue that ejection phenomena from accreting T Tauri stars most likely include three dynamical components: (1) an outer self-collimated steady disc wind carrying most of the mass-flux in the optical jet (when present); confining (2) a pressure-driven coronal stellar wind; and (3) a hot inner flow made of blobs sporadically ejected from the magnetopause. If the stellar magnetic moment is parallel to the disc magnetic field, then the highly variable inner flow resembles a "Reconnection X-wind", that has been proven to efficiently brake down an accreting and contracting young star. If the magnetic moment is anti-parallel, then larger versions of the solar coronal mass ejections are likely to occur. The relative importance of these three components in the observed outflows and the range of radii involved in the disc wind are expected to vary with time, from the stage of embedded source to the optically revealed T Tauri star phase.

Key words: accretion, accretion disks -- magnetohydrodynamics (MHD) -- stars: pre-main sequence -- ISM: jets and outflows

© ESO 2006

What is OpenURL?

The OpenURL standard is a protocol for transmission of metadata describing the resource that you wish to access.

An OpenURL link contains article metadata and directs it to the OpenURL server of your choice. The OpenURL server can provide access to the resource and also offer complementary services (specific search engine, export of references...). The OpenURL link can be generated by different means.

  • If your librarian has set up your subscription with an OpenURL resolver, OpenURL links appear automatically on the abstract pages.
  • You can define your own OpenURL resolver with your EDPS Account.
    In this case your choice will be given priority over that of your library.
  • You can use an add-on for your browser (Firefox or I.E.) to display OpenURL links on a page (see http://www.openly.com/openurlref/). You should disable this module if you wish to use the OpenURL server that you or your library have defined.