Interstellar Glycolaldehyde, Methyl Formate, and Acetic Acid I: A
  Bi-modal Abundance Pattern in Star Forming Regions
  The relative column densities of the structural isomers methyl formate,
glycolaldehyde, and acetic acid are derived for a dozen positions towards the
massive star-forming regions MM1 and MM2 in the NGC 6334I complex, which are
separated by $\sim$4000 AU. Relative column densities of these molecules are
also gathered from the literature for 13 other star-forming regions. In this
combined dataset, a clear bi-modal distribution is observed in the relative
column densities of glycolaldehyde and methyl formate. No such distribution is
evident with acetic acid. The two trends are comprised of star-forming regions
with a variety of masses, suggesting that there must be some other common
parameter that is heavily impacting the formation of glycolaldehyde. This is
indicative of some demonstrable differentiation in these cores; studying the
abundances of these isomers may provide a clue as to the integral chemical
processes ongoing in a variety of protostellar environments.
