deletions | additions       diff --git a/section_Introduction_Massive_stars_strongly__.tex b/section_Introduction_Massive_stars_strongly__.tex  index dcf4396..466ca97 100644  --- a/section_Introduction_Massive_stars_strongly__.tex  +++ b/section_Introduction_Massive_stars_strongly__.tex 
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The selection of bubbles with an overabundance of YSOs along the bubble-ISM boundary are a potentially excellent set of sources to study the mechanisms of triggered star-formation. The method of identifying YSOs through photometry, however, is limited. Robitaille \& Whitney (2006) showed that YSO age is degenerate with the observer's inclination angle. Briefly, an early-stage YSO and a late-stage YSO seen edge on, so the accretion or debris disk is observed as thick and blocking the inner regions, can appear similar, even in the IR. Thus, we require other diagnostics of the YSOs along the bubble edge to determine the youngest, and most likely to have been triggered, YSOs.   The current project aimed to identify the youngest YSOs by observing the CS (1-0) transition near 49 GHz with the Green Bank Telescope (GBT). CS is a probe of young star-formation. It has been detected in outflows from protostars, infall, disks and in hot cores \cite{1997A&A...317L..55D,1996A&AS..115...81B}. \cite{1997A&A...317L..55D,1996A&AS..115...81B,Morata_2012}.  The chemistry is, naturally, complex, and it appears that CS can play several roles. Our aim here is to use CS as a broad identifier of young star-formation and use any non-gaussian line-shapes to infer molecular gas behavior. After describing the CS survey and CS mapping observations (sec 2) and numerical results (sec 3), we analyze the Herschel-HiGAL emission toward all our sources to determine, along with our CS detections, the CS abundances (sec 4.1). We also analyze three sources for evidence of rapid infall (sec 4.2) and three mapped regions (sec 4.3). We end with a summary of the conclusions.   
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