Using observation data obtained from the NanShan 26m Radio Telescope at the Nanshan Station of the Xinjiang Astronomical Observatory (XAO) and the 13.7m telescope at the Purple Mountain Observatory in Delingha, researchers from XAO analyzed the distribution of NH3, 12CO, 13CO, and C18O, as well as the spectral line parameters of the Aquila giant molecular cloud, and derived the associated physical parameters. This work was published in Research in Astronomy and Astrophysics.
It is widely recognized that carbon-chain molecules are depleted from the gas phase in the central regions of the molecular cores due to their freeze-out onto dust grains. As a result, carbon-chain molecules are typically found in the outer regions of the molecular cores. Conversely, nitrogen-bearing molecules like ammonia are concentrated in the inner cores.
In addition, ammonia remains detectable in the gas phase because it is resistant to depletion onto dust grains. Therefore, the carbon-chain molecules and ammonia lines share some common attributes while also exhibiting distinct characteristics.
The study shows that the CO gas distribution is similar to that of NH3 in the Aquila Rift cloud complex. By comparing the spectral line parameters of NH3, 13CO, and C18O, the researchers revealed that the line center velocities of these species are comparable and positively correlated, indicating that they originate from the same emission region. However, no significant correlation was identified for other parameters, including integrated intensity, line widths, main beam brightness temperature, and the column densities of NH3, 13CO, and C18O. This study will contributes to a deeper understanding of the molecular distributions within the Aquila molecular cloud.
This research was supported by the National Key R&D Programs of China, the Tianchi Talent Project of Xinjiang Uyghur Autonomous Region, and the Natural Science Foundation of Xinjiang Uyghur Autonomous Region.
Fig.1. The composite maps of integrated intensity of colored 12CO (left) with the contour lines NH3 (1,1), colored 13CO (middle) with the contour lines NH3 (1,1), and colored C18O (right) with the contour lines NH3(1,1) in the Aquila Rift cloud complex.
Fig.2. Left: Correlation between the line center velocities of NH3 (1,1) and 13CO, C18O lines at corresponding points in the Aquila Rift cloud complex. Right: Histograms showing the distributions of measured line center velocity for NH3 (1,1), 13CO, and C18O.
