The Alma catalog of OB stars. II. A cross-match with Gaia DR2 and an
  updated map of the solar neighbourhood
  We cross-match the Alma catalog of OB stars with Gaia DR2 astrometry and
photometry as a first step towards producing a clean sample of massive stars in
the solar neighbourhood with a high degree of completeness. We analyze the
resulting colour-absolute magnitude diagram to divide our sample into
categories and compare extinction estimates from two sources, finding problems
with both of them. The distances obtained with three different priors are found
to have few differences among them, indicating that Gaia DR2 distances are
robust. An analysis of the 3-D distribution of massive stars in the solar
neighbourhood is presented. We show that a kinematically distinct structure we
dub the Cepheus spur extends from the Orion-Cygnus spiral arm towards the
Perseus arm and is located above the Galactic mid-plane, likely being related
to the recently discovered Radcliffe wave. We propose that this corrugation
pattern in the Galactic disk may be responsible for the recent enhanced star
formation at its crests and troughs. We also discuss our plans to extend this
work in the immediate future.
