TY - JOUR
T1 - Nobeyama 45 m Cygnus-X CO Survey. I. Photodissociation of Molecules Revealed by the Unbiased Large-scale CN and C18O Maps
AU - Yamagishi, M.
AU - Nishimura, A.
AU - Fujita, S.
AU - Takekoshi, T.
AU - Matsuo, M.
AU - Minamidani, T.
AU - Taniguchi, K.
AU - Tokuda, K.
AU - Shimajiri, Y.
N1 - Funding Information:
We express many thanks to the anonymous referee for useful comments. This work is based on observations with the 45 m telescope at the Nobeyama Radio Observatory (NRO). NRO is a branch of the National Astronomical Observatory of Japan, National Institutes of Natural Sciences. This work is also based on archival data obtained with the Herschel Space Observatory (Observation IDs: 1342244168, 1342257386, 1342196917, 1342244170, 1342211307, 1342257384). Data analysis was carried out on the open use data analysis computer system at the Astronomy Data Center, ADC, of the National Astronomical Observatory of Japan. This research is supported by JSPS KAKENHI grant No. JP17K14261.
Publisher Copyright:
© 2018. The American Astronomical Society. All rights reserved..
PY - 2018/3
Y1 - 2018/3
N2 - We present an unbiased large-scale (9 deg2) CN (N = 1-0) and C18O (J = 1-0) survey of Cygnus-X conducted with the Nobeyama 45 m Cygnus-X CO survey. CN and C18O 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/C18O 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/C18O ratios are enhanced via photodissociation reactions. We investigate the relation between the CN/C18O ratio and strength of the UV radiation field. As a result, we find that CN/C18O ratios correlate with the far-UV intensities, G 0. We also find that CN/C18O ratios decrease inside molecular clouds, where the interstellar UV radiation is reduced due to the interstellar dust extinction. We conclude that the CN/C18O ratio is controlled by the UV radiation, and is a good probe of photon-dominated regions.
AB - We present an unbiased large-scale (9 deg2) CN (N = 1-0) and C18O (J = 1-0) survey of Cygnus-X conducted with the Nobeyama 45 m Cygnus-X CO survey. CN and C18O 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/C18O 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/C18O ratios are enhanced via photodissociation reactions. We investigate the relation between the CN/C18O ratio and strength of the UV radiation field. As a result, we find that CN/C18O ratios correlate with the far-UV intensities, G 0. We also find that CN/C18O ratios decrease inside molecular clouds, where the interstellar UV radiation is reduced due to the interstellar dust extinction. We conclude that the CN/C18O ratio is controlled by the UV radiation, and is a good probe of photon-dominated regions.
UR - http://www.scopus.com/inward/record.url?scp=85044161550&partnerID=8YFLogxK
UR - http://www.scopus.com/inward/citedby.url?scp=85044161550&partnerID=8YFLogxK
U2 - 10.3847/1538-4365/aaab4b
DO - 10.3847/1538-4365/aaab4b
M3 - Article
AN - SCOPUS:85044161550
SN - 0067-0049
VL - 235
JO - Astrophysical Journal, Supplement Series
JF - Astrophysical Journal, Supplement Series
IS - 1
M1 - 9
ER -