AAS 198th Meeting, June 2001
Session 28. Winds and Outflows
Oral, Monday, June 4, 2001, 2:00-3:30pm, C105

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[28.01] Heating and Ionization of X-Winds

H. Shang (ASIAA/CfA), A. E. Glassgold, F. H. Shu (UCB), S. Lizano (UNAM)

We formulate the physical basis for a streamline-by-streamline integration of the ionization and heat equations of the steady x-wind. In addition to th well-known processes associated with the interaction of stellar and accretion-funnel hot-spot radiation with the wind, we include X-ray heating and ionization, mechanical heating, and a new calculation of ambipolar diffusion heating. The mechanical heating arises from the fluctuations produced by the time dependent x-wind star-disk interaction, which generates magnetic fluctuations at the source that are carried by the wind to large distances where they are dissipated in shocks, MHD waves, and turbulent cascades. We model the time-averaged heating by the scale-free volumetric heating rate \Gamma\rm mech = \alpha \rho v3 s-1, where \rho and v are the local mass density and wind speed, respectively, s is the distance from the origin, and \alpha is a phenomenological constant. When we consider a revealed but active young stellar object, we find that choosing \alpha ~10-3 in our numerical calculations produces temperatures and electron fractions that are high enough for the x-wind jet to radiate in the optical forbidden lines at the level and on the spatial and kinematic scales that are observed. We also discuss a variety of applications of our thermal-chemical calculations that lead to further observational checks of the theory. This research has been supported in part by the NSF.

The author(s) of this abstract have provided an email address for comments about the abstract: hshang@cfa.harvard.edu

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