On the source of dense outflows from T Tauri Stars. and III. Winds driven from the star-disc shear layer

Abstract

Ultraviolet observations of classical T Tauri Stars (cTTSs) have shown that there is a hot (Te ~ 80,000 K) and dense (ne ~ 1e10 cm-3) component associated with the large scale jet. This hot component is formed very close to the base of the jet providing fundamental information on the jet formation mechanism. In this series, we have investigated whether this component can be formed in disc winds, either cool or warm. To conclude the series, jet launching from the interface between the magnetic rotor (the star) and the disc is studied. Synthetic profiles are calculated from numerical simulations of outflow launching by star-disc interaction. Profiles are calculated for several possible configurations of the stellar field: dipolar (with surface strengths, B of 1, 2 and 5 kG) or dynamo fed. Also two types of discs, passive or subjected to an alpha/Omega-dynamo, are considered. These profiles have been used to define the locus of the various models in the observational diagram: dispersion versus centroid, for the profiles of the SiIII] line. Bulk motions produce an increasing broadening of the profile as the lever arm launching the jet becomes more efficient; predicted profiles are however, sensitive to the disc inclination. Models are compared with observations of the SiIII] lines obtained with the Hubble Space Telescope. In addition, it is shown that the non-stationary nature of star-disc winds produce a flickering of the profile during quiescence with variations in the line flux of about 10%. At outburst, accretion signatures appear in the profiles together with an enhancement of the wind, producing the correlation between accretion and outflow as reported from RU Lup, AA Tau and RW Aur observations.

10 figures, Monthly Notices of the Royal Astronomical Society, in press

References in corpus (11)

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• How Hot is the Wind from TW Hydrae?
• Outflows and accretion in a star--disc system with stellar magnetosphere and disc dynamo
• Periodic radial velocity variations in RU Lupi
• Evidence for stellar driven outflows from the Classical T Tauri star RY Tau
• Stellar dynamo driven wind braking instead of disc coupling
• The formation of planetary disks and winds: an ultraviolet view

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• The structure and spectrum of the accretion shock in the atmospheres of young stars
• Evidence of non-thermal X-ray emission from HH 80
• Evidence of hot high velocity photoionized plasma falling on actively accreting T-Tauri Stars
• Non-LTE Modelling of the Structure and Spectra of the Hot Accretion Spots on the Surface of Young Stars
• X-ray emission from stellar jets by collision against high-density molecular clouds: an application to HH 248
• On the source of the Fe K-alpha emission in T Tauri Stars. Radiation induced by relativistic electrons during flares. An application to RY Tau