H2CO and H110{\alpha} observations towards NH3 sources

TL;DR

This study used radio observations to detect H2CO and H110α lines in NH3 sources, revealing their distribution, correlation with extinction, and differences in abundance ratios across clouds.

Contribution

It provides new detections of H2CO lines, compares their properties with NH3 and 13CO, and analyzes their distribution and abundance variations in different clouds.

Findings

H2CO detection rate correlates better with extinction than background radiation.

Line velocities of H2CO and NH3 agree well.

H2CO is distributed on larger scales than NH3, similar to 13CO.

Abstract

We observed the H2CO(110-111) absorption lines and H110{\alpha} radio recombination lines (RRL) toward 180 NH3 sources using the Nanshan 25-m radio telescope. In our observation, 138 sources were found to have H2CO lines and 36 have H110{\alpha} RRLs. Among the 138 detected H2CO sources, 38 sources were first detected. The detection rates of H2CO have a better correlation with extinction than with background continuum radiation. Line center velocities of H2CO and NH3 agree well. The line width ratios of H2CO and NH3 are generally larger than 1 and are similar to that of 13CO. The correlation between column densities of H2CO and extinction is better than that between NH3 and extinction. These line width relation and column density relation indicate H2CO is distributed on a larger scale than that of NH3, being similar to the regions of 13CO. The abundance ratios between NH3 and H2CO were found to be different in local clouds and other clouds.