The spiral pattern rotation speed of the Galaxy and the corotation
  radius with GAIA DR2
  In this work we revisit the issue of the rotation speed of the spiral arms
and the location of the corotation radius of our Galaxy. This research was
performed using homogeneous data set of young open clusters (age < 50 Myr)
determined from Gaia DR2 data. The stellar astrometric membership were
determined using proper motions and parallaxes, taking into account the full
covariance matrix. The distance, age, reddening and metallicity of the clusters
were determined by our non subjective multidimensional global optimization tool
to fit theoretical isochrones to Gaia DR2 photometric data. The rotation speed
of the arms is obtained from the relation between age and angular distance of
the birthplace of the clusters to the present-day position of the arms. Using
the clusters belonging to the Sagittarius-Carina, Local and Perseus arms, and
adopting the Galactic parameters $R_0$ = 8.3 kpc and $V_0$ = 240 km\,s$^{-1}$,
we determine a pattern speed of $28.2 \pm 2.1$ km\,s$^{-1}$\,kpc$^{-1}$, with
no difference between the arms. This implies that the corotation radius is $R_c
= 8.51 \pm 0.64$ kpc, close to the solar Galactic orbit ($R_c/R_0 =
1.02\pm0.07$).
