ATLASGAL-selected massive clumps in the inner Galaxy III. Dust Continuum
  Characterization of an Evolutionary Sample
  The ATLASGAL survey provides an ideal basis for detailed studies of large
numbers of massive star forming clumps covering the whole range of evolutionary
stages. The ATLASGAL Top100 is a sample of clumps selected from their infrared
and radio properties to be representative for the whole range of evolutionary
stages. The ATLASGAL Top100 sources are the focus of a number of detailed
follow-up studies that will be presented in a series of papers. In the present
work we use the dust continuum emission to constrain the physical properties of
this sample and identify trends as a function of source evolution.
  We determine flux densities from mid-infrared to submm wavelength (8-870
micron) images and use these values to fit their spectral energy distributions
(SEDs) and determine their dust temperature and flux. Combining these with
recent distances from the literature including maser parallax measurements we
determine clump masses, luminosities and column densities. We find trends for
increasing temperature, luminosity and column density with the proposed
evolution sequence, confirming that this sample is representative of different
evolutionary stages of massive star formation. We show that most of the sample
has the ability to form massive stars (including the most massive O-type stars)
and that the majority is gravitationally unstable and hence likely to be
collapsing.
  The highest column density ATLASGAL sources presented cover the whole range
of evolutionary stages from the youngest to the most evolved high-mass star
forming clumps. Their study provides a unique starting point for more in-depth
research on massive star formation in four distinct evolutionary stages whose
well defined physical parameters afford more detailed studies. As most of the
sample is closer than 5 kpc, these sources are also ideal for follow-up
observations with high spatial resolution.
