2019/07/24 by M. S. Kirsanova, Ya N. Pavlyuchenkov, Ya. N. Pavlyuchenkov +9 · 1 citation
Physics and Astronomy · #Astro and Planetary Science #Astronomy #Astrophysics #Astrophysics and Star Formation Studies #Circumstellar envelope #Condensation #Emission spectrum #Envelope (radar) #Extinction (optical mineralogy) #Galaxy #Geometry #Infrared #Interstellar cloud #Interstellar medium #Line (geometry) #Molecular cloud #Optical depth #Optics #Physics #Ring (chemistry) #Spectral line #Stars #Stellar, planetary, and galactic studies #astro-ph.GA #astro-ph.SR
paper · pdf · doi:10.1093/mnras/stz2048
accepted to MNRAS
openalex publication_date 2019/07/24 · arxiv created 2019/08/15 · arxiv updated 2019/08/16 · openalex created_date 2025/10/10 · openalex updated_date 2026/08/05
ABSTRACT The H ii region RCW 120 is a well-known object, which is often considered as a target to verify theoretical models of gas and dust dynamics in the interstellar medium. However, the exact geometry of RCW 120 is still a matter of debate. In this work, we analyse observational data on molecular emission in RCW 120 and show that 13CO(2–1) and C18O(2–1) lines are fitted by a 2D model representing a ring-like face-on structure. The changing of the C18O(3–2) line profile from double-peaked to single-peaked from the dense molecular Condensation 1 might be a signature of stalled expansion in this direction. In order to explain a self-absorption dip of the 13CO(2–1) and 13CO(3–2) lines, we suggest that RCW 120 is surrounded by a diffuse molecular cloud, and find confirmation of this cloud on a map of interstellar extinction. Optically thick 13CO(2–1) emission and the infrared 8 μm PAH band form a neutral envelope of the H ii region resembling a ring, while the envelope breaks into separate clumps on images made with optically thin C18O(2–1) line and far-infrared dust emission.