H2CO and H110α Observations toward the Aquila Molecular Cloud

The formaldehyde H2CO(1(10) -1(11) ) absorption line and H110 alpha radio recombination line have been observed toward the Aquila Molecular Cloud using the Nanshan 25 m telescope operated by the Xinjiang Astronomical Observatory CAS. These first observations of the H2CO (1(10) -1(11) ) absorption line determine the extent of the molecular regions that are affected by the ongoing star formation in the Aquila molecular complex and show some of the dynamic properties. The distribution of the excitation temperature T-ex for H2CO identifies the two known star formation regions W40 and Serpens South as well as a smaller new region Serpens 3. The intensity and velocity distributions of H2CO and (CO)-C-13(1-0) do not agree well with each other, which confirms that the H2CO absorption structure is mostly determined by the excitation of the molecules resulting from the star formation rather than by the availability of molecular material as represented by the distribution. Some velocity-coherent linear (CO)-C-13(1-0) structures have been identified in velocity channel maps of H2CO and it is found that the three star formation regions lie on the intersect points of filaments. The H110 alpha emission is found only at the location of the W40 H II region and spectral profile indicates a redshifted spherical outflow structure in the outskirts of the H II region. Sensitive mapping of H2CO absorption of the Aquila Complex has correctly identified the locations of star formation activity in complex molecular clouds and the spectral profiles reveal the dominant velocity components and may identify the presence of outflows.