2018/01/28 by M. Yamagishi, A. Nishimura, S. Fujita +6 · 15 citations
Physics and Astronomy · #Analytical Chemistry (journal) #Astrochemistry #Astrophysical Phenomena and Observations #Astrophysics and Star Formation Studies #Interstellar medium #Irradiation #Molecule #Photodissociation #Radiation #Stellar, planetary, and galactic studies #astro-ph.GA
paper · pdf · doi:10.3847/1538-4365/aaab4b
published in The Astrophysical Journal Supplement Series 235(1), 9 (Institute of Physics) · 16 pages, 7 figures, ApJS accepted
arxiv created 2018/01/28 · openalex created_date 2018/02/23 · openalex publication_date 2018/03/01 · arxiv updated 2018/03/21 · openalex updated_date 2026/08/05
Abstract We present an unbiased large-scale (9 deg 2 ) CN ( N = 1–0) and C 18 O ( J = 1–0) survey of Cygnus-X conducted with the Nobeyama 45 m Cygnus-X CO survey. CN and C 18 O are detected in various objects toward the Cygnus-X North and South (e.g., DR17, DR18, DR21, DR22, DR23, and W75N). We find that CN/C 18 O integrated intensity ratios are systematically different from region to region, and are especially enhanced in DR17 and DR18, which are irradiated by the nearby OB stars. This result suggests that CN/C 18 O ratios are enhanced via photodissociation reactions. We investigate the relation between the CN/C 18 O ratio and strength of the UV radiation field. As a result, we find that CN/C 18 O ratios correlate with the far-UV intensities, G 0 . We also find that CN/C 18 O ratios decrease inside molecular clouds, where the interstellar UV radiation is reduced due to the interstellar dust extinction. We conclude that the CN/C 18 O ratio is controlled by the UV radiation, and is a good probe of photon-dominated regions.