Large scale star formation in Auriga region
  New observations in the $VI$ bands along with archival data from the 2MASS
and $WISE$ surveys have been used to generate a catalog of young stellar
objects (YSOs) covering an area of about $6^\circ\times6^\circ$ in the Auriga
region centered at $l\sim173^\circ$ and $b\sim1^\circ.5$. The nature of the
identified YSOs and their spatial distribution are used to study the star
formation in the region. The distribution of YSOs along with that of the
ionized and molecular gas reveals two ring-like structures stretching over an
area of a few degrees each in extent. We name these structures as Auriga
Bubbles 1 and 2. The center of the Bubbles appears to be above the Galactic
mid-plane. The majority of Class\,{\sc i} YSOs are associated with the Bubbles,
whereas the relatively older population, i.e., Class\,{\sc ii} objects are
rather randomly distributed. Using the minimum spanning tree analysis, we found
26 probable sub-clusters having 5 or more members. The sub-clusters are between
$\sim$0.5 pc - $\sim$ 3 pc in size and are somewhat elongated. The star
formation efficiency in most of the sub-cluster region varies between 5$\%$ -
20$\%$ indicating that the sub-clusters could be bound regions. The radii of
these sub-clusters also support it.
