Stellar cores in the Sh 2-305 H II region
  Using our deep optical and near-infrared photometry along with
multiwavelength archival data, we here present a detailed study of the Galactic
H II region Sh 2-305, to understand the star/star-cluster formation. On the
basis of excess infra-red emission, we have identified 116 young stellar
objects (YSOs) within a field of view of ~ 18.5 arcminute x 18.5 arcminute,
around Sh 2-305. The average age, mass and extinction (A_V) for this sample of
YSOs are 1.8 Myr, 2.9 solar mass and 7.1 mag, respectively. The density
distribution of stellar sources along with minimal spanning tree calculations
on the location of YSOs reveals at least three stellar sub-clusterings in Sh
2-305. One cluster is seen toward the center (i.e., Mayer 3), while the other
two are distributed toward the north and south directions. Two massive O-type
stars (VM2 and VM4; ages ~ 5 Myr) are located at the center of the Sh 2-305 H
II region. The analysis of the infrared and radio maps traces the photon
dominant regions (PDRs) in the Sh 2-305. Association of younger generation of
stars with the PDRs is also investigated in the Sh 2-305. This result suggests
that these two massive stars might have influenced the star formation history
in the Sh 2-305. This argument is also supported with the calculation of
various pressures driven by massive stars, slope of mass function/K-band
luminosity function, star formation efficiency, fraction of Class I sources,
and mass of the dense gas toward the sub-clusterings in the Sh 2-305.
