deletions | additions       diff --git a/section_Introduction_Observations_are_painting__.tex b/section_Introduction_Observations_are_painting__.tex  index 7a41c62..c787b39 100644  --- a/section_Introduction_Observations_are_painting__.tex  +++ b/section_Introduction_Observations_are_painting__.tex 
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In this respect, two key observational findings are relevant: (i) The direct detection of luminous precursors in the month before the   major explosion of SN2009ip associated with the ejection of $\sim0.1\,\rm{M_{\odot}}$ of material (Margutti et al., 2014). (ii) Evidence for significant modulations in the radio light-curves of hydrogen-stripped SNe (i.e. SNe Ib/c; Soderberg et al., 2006, Milisavljevic et al., 2013). This latter finding indicates that a complex environment, sculpted and enriched by a significantly \emph{non-steady} mass loss of the progenitor system in the years before the explosion, surrounds some Type Ib/c SNe.  The two findings above suggest that massive stars might lose their hydrogen envelopes through explosive mass ejections (instead of steady winds, as it has been assumed so far) on time scales of months to decades before the core-collapse (i.e. much shorter than previously thought).