Families of dynamically hot stellar systems over ten orders of magnitude
  in mass
  Dynamically hot stellar systems, whether star clusters or early-type
galaxies, follow well-defined scaling relations over many orders of magnitudes
in mass. These fundamental plane relations have been subject of several
studies, which have been mostly confined to certain types of galaxies and/or
star clusters so far. Here, we present a complete picture of hot stellar
systems ranging from faint galaxies and star clusters of only a few hundred
solar masses up to giant ellipticals (gEs) with 10^12 M_sun, in particular
including large samples of compact ellipticals (cEs), ultra-compact dwarf
galaxies (UCDs), dwarf ellipticals (dEs) of nearby galaxy clusters and Local
Group ultra-faint dwarf spheroidals (dSphs). For all those stellar systems we
show the effective radius-luminosity, effective radius-stellar mass, and
effective mass surface density-stellar mass plane. Two families of hot stellar
systems can be differentiated: the 'galaxian' family, ranging from gEs over Es
and dEs to dSphs, and the 'star cluster' family, comprising globular clusters
(GCs), UCDs and nuclear star clusters (NCs). Interestingly, massive ellipticals
have a similar size-mass relation as cEs, UCDs and NCs, with a clear common
boundary towards minimum sizes. No object of either family is located in the
'zone of avoidance' beyond this limit. Even the majority of early-type galaxies
at high redshift obeys this relation. The sizes of dEs and dSphs as well as GCs
barely vary with mass over several orders of magnitude. We use the constant
galaxy sizes to derive the distances of several local galaxy clusters. Both,
galaxies and star clusters, do not exceed a surface density of \Sigma_eff =
3.17*10^{10}*M^{-3/5} M_sun pc^{-2}, causing an orthogonal kink in the galaxy
sequence for ellipticals more massive than 10^{11} M_sun. The densest stellar
systems (within their effective radius) are nuclear star clusters. (abridged)
