Infrared and radio study of star-forming regions associated with IRAS 19111+1048 and IRAS 19110+1045

Abstract

A multiwavelength study of the star-forming regions associated with IRAS 19111+1048 and IRAS 19110+1045 has been carried out. These have been simultaneously mapped in two far-infrared bands at λ_eff = 130 and 200 µm with ~1' angular resolution using the TIFR 1 m balloon-borne telescope. The radio emission from the ionized gas of these regions has been imaged at 1280, 610, and 325 MHz using the Giant Metrewave Radio Telescope, India. Assuming the detected compact sources to represent exciting zero-age main sequence (ZAMS) stars, the initial mass function [ξ(m) ∝m^-a] for the IRAS 19111+1048 region is found to be quite steep, with a = 5.3 ± 0.5 for the mass range 14 < m/M < 33. The near-infrared (NIR) source coincident with the IRAS 19111+1048 peak is likely to be an embedded pre-main-sequence star. The spectral types of the ZAMS stars inferred independently from the radio and NIR measurements match very well for a good fraction of the radio sources having NIR counterparts. The best-fit radiative transfer models of the two IRAS sources are in good agreement with the observed spectral energy distributions. A uniform density distribution of dust and gas is implied for both the sources. The extents of ionized gas, number of ZAMS stars, presence of deeply embedded sources, and lower value of L/M for the cloud support the youth of IRAS 19110+1045 vis-a-vis its neighbor, IRAS 19111+1048, consistent with earlier studies.