deletions | additions       diff --git a/jets_x ray.tex b/jets_x ray.tex  index 8807a30..c6c902d 100644  --- a/jets_x ray.tex  +++ b/jets_x ray.tex 
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We can distinguish three different X-ray emitting regions in the DG~Tau system: First, hard emission from the central star is observed with stellar flares as seen on many other young and active stars. Second, weak and soft emission from the jet is resolved several hundred AU from the star itself. Third, additional soft X-rays are emitted close to, but not from the star, because they are subject to a much smaller absorbing column density than the central, coronal source. The centroid of the spatial distribution of soft X-rays is consistent with a position on the jet axis 30-40~AU from the star \citep{2008A&A...488L..13S,2011ASPC..448..617G} in every epoch. Thus, the jet X-ray emission appears stationary in contrast to the moving, lower temperature jet material. The temperature of this inner emission region is remarkably stable over one decade between 3 and 4~MK; the maximum change observed is about 25\,\%. The change in luminosity is 1.6 in the same time range ($L_X=1-2\times10^{30}\textrm{ erg s}^{-1}$) \citep{SchneiderDGTauXray}.  There is no reason to believe that the DG~Tau system represents exceptional physical conditions for jet launching. While the inclination and absorption are less favorable to observe X-ray emission very close to the star for \textbf{most} most  other CTTS systems, there are indications that \object{HH 154} also shows an inner, stationary X-ray component and additional emission in the knots \citep{2011A&A...530A.123S,2011ApJ...737...54B} and that the X-ray emission in the more massive Herbig Ae/Be star \object{HD 163296} is extended in the direction of the jet by a few dozen AU, too \citep{2005ApJ...628..811S,2009A&A...494.1041G,2013A&A...552A.142G}. In \citet{2009A&A...493..579G} we showed that the soft X-ray emission close to DG~Tau can be explained by shock heating of a jet component moving with 400-500~km~s$^{-1}$. The mass flux in this component is less than $10^{-3}$ of the total mass flux in the jet or even lower if the same material is reheated in several consecutive shocks. If the density in the fast outflow is $>10^5$~cm$^{-3}$ then the cooling length of this shock is only a few AU and it would be invisible in current optical and IR observations, since it would be surrounded and outshone by the more luminous emission from more massive, but slower jet components. However, the stationary nature of the X-ray emission was not addressed in that article. Other models for the high-energy emission for stellar jets are discussed in the next section.