Hydrogen recombination lines near 327 MHz-II: a galactic plane survey with a 2°×6' beam

Abstract

In a previous paper we presented a low-resolution (2°×2°) survey of radio recombination lines (RRLs) at 327 MHz in the longitude range l=330° to 0° to 89°. In this paper, we present the results of a higher resolution (2°×6') survey of RRLs from seven 2°-wide fields and two 6°-wide fields in the same longitude range. Observations were made using the Ooty Radio Telescope (ORT). A total of 252 spectra that were obtained are presented. RRLs were detected in almost all the individual positions within the fields with l < 35° and at several individual positions within the fields in the longitude rangel = 35° to 85°. Detailed analysis of the data towards the field centered at G45.5+0.0, shows that the line emission consists of discrete zones of ionized gas. The angular extent of these zones are likely to be one degree or more corresponding to a linear size of > 110 pc at the kinematic distance.