Star formation in the Sh 2-53 region influenced by accreting molecular
  filaments
  We present a multi-wavelength analysis of a $\sim$30$' \times$30$'$ area
around the Sh 2-53 region (hereafter S53 complex), which is associated with at
least three H II regions, two mid-infrared bubbles (N21 and N22), and infrared
dark clouds. The $^{13}$CO line data trace the molecular content of the S53
complex in a velocity range of 36--60 km s$^{-1}$, and show the presence of at
least three molecular components within the selected area along this direction.
Using the observed radio continuum flux of the H II regions, the derived
spectral types of the ionizing sources agree well with the previously reported
results. The S53 complex harbors clusters of young stellar objects (YSOs) that
are identified using the photometric 2--24 $\mu$m magnitudes. It also hosts
several massive condensations (3000-30000 $M_\odot$) which are traced in the
{\em Herschel} column density map. The complex is found at the junction of at
least five molecular filaments, and the flow of gas toward the junction is
evident in the velocity space of the $^{13}$CO data. Together, the S53 complex
is embedded in a very similar "hub-filament" system to those reported in Myers,
and the active star formation is evident towards the central "hub" inferred by
the presence of the clustering of YSOs.
