A new distance to the Brick, the dense molecular cloud G0.253+0.016
  We analyse the near infrared colour magnitude diagram of a field including
the giant molecular cloud G0.253+0.016 (a.k.a. The Brick) observed at high
spatial resolution, with HAWK-I at the VLT. The distribution of red clump stars
in a line of sight crossing the cloud, compared with that in a direction just
beside it, and not crossing it, allow us to measure the distance of the cloud
from the Sun to be 7.20, with a statistical uncertainty of +/-0.16 and a
systematic error of +/-0.20 kpc. This is significantly closer than what is
generally assumed, i.e., that the cloud belongs to the near side of the central
molecular zone, at 60 pc from the Galactic center. This assumption was based on
dynamical models of the central molecular zone, observationally constrained
uniquely by the radial velocity of this and other clouds. Determining the true
position of the Brick cloud is relevant because this is the densest cloud of
the Galaxy not showing any ongoing star formation. This puts the cloud off by 1
order of magnitude from the Kennicutt-Schmidt relation between the density of
the dense gas and the star formation rate. Several explanations have been
proposed for this absence of star formation, most of them based on the
dynamical evolution of this and other clouds, within the Galactic center
region. Our result emphasizes the need to include constraints coming from
stellar observations in the interpretation of our Galaxy central molecular
zone.
