ATLASGAL -- Evolutionary trends in high-mass star formation
  ATLASGAL is a 870-mircon dust survey of 420 square degrees of the inner
Galactic plane and has been used to identify ~10 000 dense molecular clumps.
Dedicated follow-up observations and complementary surveys are used to
characterise the physical properties of these clumps, map their Galactic
distribution and investigate the evolutionary sequence for high-mass star
formation. The analysis of the ATLASGAL data is ongoing: we present an
up-to-date version of the catalogue. We have classified 5007 clumps into four
evolutionary stages (quiescent, protostellar, young stellar objects and HII
regions) and find similar numbers of clumps in each stage, suggesting a similar
lifetime. The luminosity-to-mass (L/M) ratio curve shows a smooth distribution
with no significant kinks or discontinuities when compared to the mean values
for evolutionary stages indicating that the star-formation process is
continuous and that the observational stages do not represent fundamentally
different stages or changes in the physical mechanisms involved. We compare the
evolutionary sample with other star-formation tracers (methanol and water
masers, extended green objects and molecular outflows) and find that the
association rates with these increases as a function of evolutionary stage,
confirming that our classification is reliable. This also reveals a high
association rate between quiescent sources and molecular outflows, revealing
that outflows are the earliest indication that star formation has begun and
that star formation is already ongoing in many of the clumps that are dark even
at 70 micron.
