Abstract:
Bright-rimmed clouds (BRCs), illuminated and shaped by nearby OB stars, are potential
sites of recent/ongoing star formation. Here we present an optical and infrared photometric
study of three BRCs: BRC 5, BRC 7 and BRC 39 to obtain a census of the young stellar
population, thereby inferring the star formation scenario, in these regions. In each BRC, the
Class I sources are found to be located mostly near the bright rim or inside the cloud, whereas
the Class II sources are preferentially outside, with younger sources closer to the rim. This
provides strong support to sequential star formation triggered by radiation-driven implosion
due to the ultraviolet radiation. Moreover, each BRC contains a small group of young stars
being revealed at its head, as the next-generation stars. In particular, the young stars at the
heads of BRC 5 and BRC 7 are found to be intermediate-/high-mass stars, which, under proper
conditions, may themselves trigger further star birth, thereby propagating star formation out
to long distances.
