Star formation in bright-rimmed clouds and cluster associated with W5 E H{\sc ii} region

Abstract

The aim of this paper is to present the results of photometric investigations of the central cluster of the W5 E region as well as a follow-up study of the triggered star formation in and around bright-rimmed clouds (BRCs). We have carried out wide field $UBVI_c$ and deep $VI_c$ photometry of the W5 E H{\sc ii} region. A distance of $\sim$2.1 kpc and a mean age of $\sim$1.3 Myr have been obtained for the central cluster. The young stellar objects (YSOs) associated with the region are identified on the basis of near-infrared and mid-infrared observations. We confirmed our earlier results that the average age of the YSOs lying on/inside the rim are younger than those lying outside the rim. The global distribution of the YSOs shows an aligned distribution from the ionising source to the BRCs. These facts indicate that a series of radiation driven implosion processes proceeded from near the central ionising source towards the periphery of the W5 E H{\sc ii} region. We found that, in general, the age distributions of the Class II and Class III sources are the same. This result is apparently in contradiction with the conclusion by Bertout, Siess & Cabrit (2007) and Chauhan et al. (2009) that classical T Tauri stars evolve to weak-line T Tauri stars. The initial mass function of the central cluster region in the mass range $0.4 \le M/M_\odot \le 30$ can be represented by $\Gamma = -1.29 \pm 0.03$. The cumulative mass functions indicate that in the mass range $0.2 \le M/M_\odot \le 0.8$, the cluster region and BRC NW have more low mass YSOs in comparison to BRCs 13 and 14.