Strong dependence of the physical properties of cores on spatial
  resolution in observations and simulations
  During the last decade in star formation research, many studies have targeted
low- and high-mass star formation regions located at different distances, with
different telescopes having specific angular resolution capabilities. We
present a systematic investigation of the angular resolution effects, with
special attention being paid to the derived masses of sources as well as the
shape of the resulting source mass functions (SMFs). We tested the impact of
angular resolution, from 0.6 down to 0.02 pc, in two star-forming regions
observed with Herschel (NGC6334 and Aquila), and three (magneto)-hydrodynamical
simulations. We detected and measured sources at each resolution using getsf
and we analysed the derived masses and sizes of the sources. We find that the
number of sources does not converge from 0.6 to 0.05 pc. It increases by about
two when the angular resolution increases with a similar factor. Below 0.05 pc,
the number of source still increases by about 1.3 when the angular resolution
increases by two, suggesting that we are close to, but not yet at, convergence.
We find that the measured sizes and masses of sources linearly depend on the
angular resolution with no sign of convergence to a resolution-independent
value. The corresponding SMF peak also shifts with angular resolution, while
the slope of the high-mass tail of the SMFs remains almost invariant. If
prestellar cores, physically distinct from their background, exist in
cluster-forming molecular clouds, we conclude that their mass must be lower
than reported so far in the literature. We discuss various implications for the
studies of star formation: the problem of determining the mass reservoirs
involved in the star-formation process; the inapplicability of the Gaussian
beam deconvolution to infer source sizes; and the impossibility to determine
the efficiency of the mass conversion from the cores to the stars.
