Studies of the distinct regions due to CO selective dissociation in the Aquila molecular cloud

¹ Xinjiang Astronomical Observatory, Chinese Academy of Sciences, Urumqi 830011, PR China
e-mail: komesh.t@outlook.com; jarken@xao.ac.cn
² University of the Chinese Academy of Sciences, Beijing 100080, PR China
³ Department of Solid State Physics and Nonlinear Physics, Faculty of Physics and Technology, Al-Farabi Kazakh National University, Almaty 050040, Kazakhstan
⁴ Netherlands Institute for Radio Astronomy, ASTRON, 7991 PD Dwingeloo, The Netherlands
e-mail: baan@astron.nl
⁵ Key Laboratory of Radio Astronomy, Chinese Academy of Sciences, Urumqi 830011, PR China
⁶ The Department of Physics, Faculty of Science, University of Malaya, 50603 Kuala Lumpur, Malaysia

Received: 10 June 2020
Accepted: 26 October 2020

Abstract

Aims. We investigate the role of selective dissociation in the process of star formation by comparing the physical parameters of protostellar-prestellar cores and the selected regions with the CO isotope distributions in photo-dissociation regions. We seek to understand whether there is a better connection between the evolutionary age of star forming regions and the effect of selective dissociation

Methods. We used wide-field observations of the ¹²CO, ¹³CO, and C¹⁸O (J = 1–0) emission lines to study the ongoing star formation activity in the Aquila molecular region, and we used the 70 and 250 μm data to describe the heating of the surrounding material and as an indicator of the evolutionary age of the core.

Results. The protostellar-prestellar cores are found at locations with the highest C¹⁸O column densities and their increasing evolutionary age coincides with an increasing 70μm/250μm emission ratio at their location. The evolutionary age of the cores may also follow from the ¹³CO versus C¹⁸O abundance ratio, which decreases with increasing C¹⁸O column densities. The original mass has been estimated for nine representative star formation regions and the original mass of the region correlates well with the integrated 70 μm flux density. Similarly, the X_¹³CO/X_C¹⁸O ratio, which provides the dissociation rate for these regions correlates with the 70 μm/250 μm flux density ratio and reflects the evolutionary age of the star formation activity.