Different Evolutionary Stages in the Massive Star Forming Region W3 Main
  Complex
  We observed three high-mass star-forming regions in the W3 high-mass star
formation complex with the Submillimeter Array and IRAM 30 m telescope. These
regions, i.e. W3 SMS1 (W3 IRS5), SMS2 (W3 IRS4) and SMS3, are in different
evolutionary stages and are located within the same large-scale environment,
which allows us to study rotation and outflows as well as chemical properties
in an evolutionary sense. While we find multiple mm continuum sources toward
all regions, these three sub-regions exhibit different dynamical and chemical
properties, which indicates that they are in different evolutionary stages.
Even within each subregion, massive cores of different ages are found, e.g. in
SMS2, sub-sources from the most evolved UCHII region to potential starless
cores exist within 30 000 AU of each other. Outflows and rotational structures
are found in SMS1 and SMS2. Evidence for interactions between the molecular
cloud and the HII regions is found in the 13CO channel maps, which may indicate
triggered star formation.
