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Christian edited Windspeed.tex
about 10 years ago
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In our model, we use a spherically symmetric stellar wind with a constant velocity. For a solar-type wind this works well for deriving the shape of the shock front because eqn.~\ref{eqn:r0} contains the kinetic energy density $\rho v^2_\infty \propto \dot M v_\infty$. However, a lower wind velocity and higher density at the equator would lead to lower post-shock temperatures with a higher emission measure close to the disk plane. ({\bf Hans: this last sentence does not connect well with the sentence before it.})
\citet{2007IAUS..243..299M} show that stellar winds from CTTS cannot have a total mass loss above $10^{-11}M_\odot\mathrm{ yr}^{-1}$ if they are launched hot. Otherwise, the high densities required to reach such a mass loss would lead to a runaway cooling. \textbf{I think we need a bit more discussion of the stellar mass loss rate, since you assume $10^{-8}$M_\odot yr$^{-1}$ above, didn't
you.} you?}
This should be observable and would probably hinder the wind launching. Thus, the winds of CTTS are probably more complex than just a scaled up version of the solar wind. Still, the wind speeds observed in the sun provide a reasonable estimate for $v_\infty$.
Figure~\ref{fig:v_infty} shows how a large $v_\infty$ and a correspondingly large ram pressure of the stellar wind push the shock front higher above the disk plane, similar to outflows with a larger $\dot M$. Additionally, $v_\infty$ is the single most important parameter that controls the maximal post-shock temperatures and the amount of hot plasma.