Investigating the physical conditions in extended system hosting
  mid-infrared bubble N14
  To observationally explore physical processes, we present a multi-wavelength
study of a wide-scale environment toward l = 13.7 - 14.9 degrees containing a
mid-infrared bubble N14. The analysis of 12CO, 13CO, and C18O gas at [31.6, 46]
km/s reveals an extended physical system (extension ~59 pc x 29 pc), which
hosts at least five groups of the ATLASGAL 870 micron dust clumps at d ~3.1
kpc. These spatially-distinct groups/sub-regions contain unstable molecular
clumps, and are associated with several Class I young stellar objects (mean age
~0.44 Myr). At least three groups of ATLASGAL clumps associated with the
expanding HII regions (including the bubble N14) and embedded infrared dark
clouds, devoid of the ionized gas, are found in the system. The observed
spectral indices derived using the GMRT and THOR radio continuum data suggest
the presence of non-thermal emission with the HII regions. High resolution GMRT
radio continuum map at 1280 MHz traces several ionized clumps powered by
massive B-type stars toward N14, which are considerably young (age ~10^3 - 10^4
years). Locally, early stage of star formation is evident toward all the groups
of clumps. The position-velocity maps of 12CO, 13CO, and C18O exhibit an
oscillatory-like velocity pattern toward the selected longitude range.
Considering the presence of different groups/sub-regions in the system, the
oscillatory pattern in velocity is indicative of the fragmentation process. All
these observed findings favour the applicability of the global collapse
scenario in the extended physical system, which also seems to explain the
observed hierarchy.
