deletions | additions       diff --git a/subsection_Infall_Three_sources_N62__.tex b/subsection_Infall_Three_sources_N62__.tex  index 262cd23..9cb7fcd 100644  --- a/subsection_Infall_Three_sources_N62__.tex  +++ b/subsection_Infall_Three_sources_N62__.tex 
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\subsection{Infall}  Three sources, N62-1, N90-2 and N117-3, have a non-gaussian line profile (see Fig. \ref{infall}). In each case the line profile is stronger on the blue-side. The line-profile of N117-3 is double-peaked with the blue-shifted peak stronger than the red-shifted peak. The line-profiles of N62-1 and N90-2 are single-peaked but with a plateau on the red-shifted side. We interpret these profiles as evidence of infall. N62-1 and N90-2 both are located in infrared dark clouds that intersect their nearby bubble (N62 and N90). Thus, infall, if present, could be triggered by an expanding HII region via the radiatively driven implosion. N117-3 is located within in the bubble, in projection. There is no obvious interpretation for this infall candidate's interaction with the associated bubble N117.  Myers et al. (1996) present a model of infall that predicts line profiles similar to these observations. They assume two clouds (near and far) falling toward a common center and estimate the the resulting line profiles accounting for optical depth effects as well as standard radial-dependencies of velocity and excitation temperature. By measuring five parameters, the Myers et al. (1996) model allows an estimate of the infall velocity. The measured parameters are: $\sigma$ (velocity dispersion of an optically thin tracer), T_{BD} T$_{BD}$  (the blue-shifted excess emission), T_{RD} (the red-shifted emission), T_D (the plateau emission), v_{red} (the red-shifted peak emission velocity) and v_{blue} (the blue-shifted peak emission velocity). When all quantities can be measured, the infall velocity is estimated to be: \begin{equation}  v_{in} \approx \frac{\sigma^2}{v_{red} - v_{blue}} \ln\left( \frac{1+e T_{BD}/T_D}{1+e T_{RD}/T_D}\right)  \end{equation} 
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