Hans Moritz Günther edited mass loss rates.tex  almost 10 years ago

Commit id: 172e54e7b47c76060181aef02fe108062bf7cc6b

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Typical mass loss rates found in the literature for CTTS outflows are in the range $10^{-10}-10^{-6}M_{\odot}\textrm{ yr}^{-1}$ \citep{1999A&A...342..717B,2006A&A...456..189P}. \citet{2006ApJ...646..319E} measure values down to $10^{-10}$~M$_{\odot}$~yr$^{-1}$ for some CTTS, but only upper limits for weak-line T Tauri stars (WTTS). In the specific case of DG~Tau \citet{1997A&A...327..671L} calculate the mass loss rate as $6.5\cdot 10^{-6}$~M$_{\odot}$~yr$^{-1}$; \citet{1995ApJ...452..736H}  obtain $3\cdot 10^{-7}$~M$_{\odot}$~yr$^{-1}$ and, further out in the jet, \citet{2000A&A...356L..41L} find $1.4\cdot 10^{-8}$~M$_{\odot}$~yr$^{-1}$. Those measurements for the optical jet are probably dominated by the disk wind \citep[e.g.][]{2014arXiv1404.0728W} and unlikely to track the stellar mass loss correctly.  \citet{2009A&A...493..579G} shows show  that a mass loss below $10^{-10}$~M$_{\odot}$~yr$^{-1}$ is sufficient to explain the X-ray emission from the jet as shock heating. We use $10^{-8}$~M$_{\odot}$~yr$^{-1}$ as fiducial stellar mass loss in the remainder of the article. This is only a fraction to the total mass loss of the system because the disk wind, though slower, operates over a much larger area and dominates the system's mass loss.  Figure~\ref{fig:dot_m} shows how a larger mass loss rate and therefore a higher density and ram pressure in the stellar wind pushes the shock front out to larger radii. The different shape of the shock front also influences the post-shock temperatures. In the high mass loss rate scenario (blue dash-dotted line) the shock front reaches its maximum radius at a height of 60~AU and most of the spherically symmetric wind passes the shock front at shallow angles, so this scenario has the highest fraction of low temperature material.