Near-Infrared Photometry and Radio Continuum Study of the Massive Star Forming Regions IRAS 21413+5442 and IRAS 21407+5441

TL;DR

This study combines near-infrared photometry and radio continuum observations to analyze two massive star forming regions, revealing stellar content, ionized regions, and potential star formation triggers, suggesting they are part of the same molecular cloud.

Contribution

It provides detailed near-infrared and radio observations of IRAS 21413+5442 and IRAS 21407+5441, identifying key stellar objects and their properties, and proposing a possible star formation trigger mechanism.

Findings

Identification of a late O type star near CO jets in IRAS 21413+5442

Detection of a compact HII region around a high-intermediate mass star cluster in IRAS 21407+5441

Evidence supporting that both IRAS sources belong to the same molecular cloud

Abstract

IRAS 21413+5442 and IRAS 21407+5441 are two massive star forming regions of high luminosity, likely associated with each other. Near-infrared photometry on these two IRAS sources was performed at UKIRT using the UFTI under excellent seeing conditions yielding an angular resolution of $\sim$ 0.5 arcsec. Our results reveal details of stellar content to a completeness limit (90%) 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) color, 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 HII region around a central high - intermediate mass star cluster. We have detected a number of sources with large (H-K) color 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 HII regions which seem to support our near-IR photometric results. Based on our radio continuum map and the archival MSX 8.2 $\mu$m 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 colors, present in between the two sources, might have triggered star formation in this region. However one can not rule out the alternative possibility that Star A could be a nearby foreground star.