Infrared photometry of YSOs in the W4 cloud complex

The surface density distribution of the young stellar objects (YSOs) reveals three new clusterings and ~50% distributed protostars in the H II region. The clusters are of low-mass nature but significantly younger than the central cluster IC 1805. We identified ~38 ETLSs in the region, a majority of which consist of one or a few stars at their tips.

We find that these stars are low-mass (<2 M_{sun}_) YSOs, located at the outskirts (>17 pc) of the cluster IC 1805 and are part of the scattered distributed population. We argued that the star formation in the ETLSs of W4 is going on possibly due to the triggering effect of the expanding W4 bubble. Although high-resolution photometric and spectroscopic data would be required to confirm the scenario, nonetheless, we discuss the implications of this scenario for our understanding of distributed low-mass star formation in cloud complexes as opposed to other mechanisms such as turbulent fragmentation and dynamical ejection.