Giant molecular clouds in M 33: are they susceptible to dynamical
  friction?
  Most of giant molecular clouds (GMCs) in M 33 are connected with spiral-like
gaseous arms (filaments) with the exception of the inner 2 kpc region where the
link between the arms and GMCs disappears (see Tosaki et al. 2011). We check
whether it may be caused by the dynamic friction retarding the clouds. Using
semi-analytical model for this galaxy we calculate the dynamics of GMCs of
different masses situated at different initial galactocentric distances in the
disk plane. We demonstrate that the dynamical friction may really change the
orbits of GMCs in the central 2 kpc-size region. However in this case the
typical lifetimes of GMCs should be close to or greater than $10^8$~yr, which
is larger than the usually accepted values.
