Near-infrared photometry and radio continuum study of the massive star-forming regions IRAS 21413+5442 and IRAS 21407+5441

Abstract

IRAS 21413+5442 and IRAS 21407+5441 are two massive star-forming regions of high luminosity, likely associated with each other. Near-infrared (NIR) photometry on these two IRAS sources was performed at United Kingdom Infrared Telescope (UKIRT) using the UFTI under excellent seeing conditions yielding an angular resolution of ∼0.5 arcsec. Our results reveal details of stellar content to a completeness limit (90 per cent) of J= 18.5, H= 18.0 and K= 17.5 mag in the two regions. In IRAS 21413+5442, we identify a late O-type star, having large H−K colour, to be near the centre of the CO jets observed by earlier authors. The UKIRT images reveal in IRAS 21407+5441, a faint but clear compact H ii region around a central high- and intermediate-mass star cluster. We have detected a number of sources with large H−K colour which are not detected in J band. We also present the GMRT radio continuum map at 1.28 GHz covering the entire region surrounding the two star-forming clouds. The radio continuum fluxes are used to estimate the properties of H ii regions which seem to support our NIR photometric results. Based on our radio continuum map and the archival Midcourse Space Experiment (MSX) 8.2-μm image, we show that the two IRAS sources likely belong to the same parent molecular cloud and conjecture that a high-mass star of large IR colours, present in between the two sources, might have triggered star formation in this region. However, one cannot rule out the alternative possibility that Star A could be a nearby foreground star.