Stellar Cores in the Sh 2-305 H ii Region

Abstract

Abstract 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 infrared emission, we have identified 116 young stellar objects (YSOs) within a field of view of ∼18.′5 × 18.′5 around Sh 2-305. The average age, mass, and extinction (A V ) for this sample of YSOs are 1.8 Myr, 2.9 M ⊙, 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 subclusterings 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 Sh 2-305. The association of the younger generation of stars with the PDRs is also investigated in Sh 2-305. This result suggests that these two massive stars might have influenced the star formation history in Sh 2-305. This argument is also supported by the calculation of various pressures driven by massive stars, the slope of the mass function/K-band luminosity function, star formation efficiency, fraction of Class i sources, and mass of the dense gas toward the subclusterings in Sh 2-305.