HCO+ and radio continuum emission from the star forming region G75.78+0.34

Abstract

We present 1.3 and 3.6cm radio continuum images and a HCO+ spectrum of the massive star forming region G75.78+0.34 obtained with the Very Large Array (VLA) and with the Berkley Illinois Maryland Association (BIMA) interferometer. Three structures were detected in the continuum emission: one associated to the well known cometary HII region, plus two more compact structures located at 6" east and at 2" south of cometary HII region. Using the total flux and intensity peak we estimated an electron density of ~1.5x10^4 cm^{-3}, an emission measure of ~6x10^{7} cm^{-6} pc, a mass of ionized gas of ~3 M_Sun and a diameter of 0.05 pc for the cometary HII region, being typical values for an ultracompact HII region. The HCO^+ emission is probably originated from the molecular outflows previously observed in HCN and CO.