Astronomy and Astrophysics – Astrophysics
Scientific paper
Sep 2005
adsabs.harvard.edu/cgi-bin/nph-data_query?bibcode=2005aipc..784..215c&link_type=abstract
MAGNETIC FIELDS IN THE UNIVERSE: From Laboratory and Stars to Primordial Structures. AIP Conference Proceedings, Volume 784, pp
Astronomy and Astrophysics
Astrophysics
Pre-Main-Sequence Stars, Magnetohydrodynamics, Astrophysical Jets, Accretion Disks, Pre-Main Sequence Objects, Young Stellar Objects And Protostars, Jets, Outflows, And Bipolar Flows, Accretion And Accretion Disks
Scientific paper
In this contribution, we consider stationary MHD ejection models from the disk surface, the star-disk corotation region (``X-wind''), and the star itself. We compare their predicted angular momentum and poloidal speeds with recent observations of T Tauri jet kinematics, and review the resulting constraints on the launch radius, magnetic lever-arm, and heat deposition in the jet (see Ferreira et al. 2005 for more details).
Cold MHD disk winds are found to predict excessive rotation in T Tauri jets and are definitely excluded, while warm MHD disk winds (including heating at the disk surface) with moderate magnetic lever arms λ = (rA/r0)2 ~= 6 - 20 reproduce very well both the observed rotation signatures and poloidal speeds, if launching radii extend to r0 ~= 0.1-3 AU. Both stellar winds and X-winds are challenged by the range of poloidal speeds in T Tauri jets: It should be checked if stellar winds can accelerate the observed jet mass-flux without excessive radiative losses, and if X-winds can sweep-up enough ambient gas to explain the intermediate-velocity components towards jet edges.
We also show that, contrary to common belief, warm self-similar disk winds are capable of reproducing the collimation, line profiles, and ejection/accretion ratio in T Tauri jets. Implications of the steady warm disk-wind hypothesis on physical conditions in T Tauri disks (e.g. the required magnetic flux) are recalled.
Cabrit Silvie
Dougados Catherine
Ferreira Jonathan
Garcia Paulo
Pesenti Nicholas
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