Please use this identifier to cite or link to this item: http://hdl.handle.net/10995/111385
 Title: Dark Cloud-type Chemistry in Photodissociation Regions with Moderate Ultraviolet Field Authors: Kirsanova, M. S.Punanova, A. F.Semenov, D. A.Vasyunin, A. I. Issue Date: 2021 Publisher: Oxford University PressOxford University Press (OUP) Citation: Dark Cloud-type Chemistry in Photodissociation Regions with Moderate Ultraviolet Field / M. S. Kirsanova, A. F. Punanova, D. A. Semenov et al. — DOI 10.2495/SAFE210031 // Monthly Notices of the Royal Astronomical Society. — 2021. — Vol. 507. — Iss. 3. — P. 3810-3829. Abstract: We present a study of emission lines of small hydrocarbons C2H and c-C3H2, and COMs precursors H2CO and CH3OH in order to better understand the possible chemical link between the molecular abundances and UV radiation field in photodissociation regions (PDRs). We study two PDRs around extended and compact H ii regions with G ≤ 50 Habings in the S235 star-forming complex. We find the highest abundances of both hydrocarbons on the edges of molecular clumps, while c-C3H2 is also abundant in the low-density expanding PDR around compact H ii region S235 A. We see the highest methanol column density towards the positions with the UV field G ≈ 20-30 Habings and explain them by reactive desorption from the dust grains. The $N_{\rm C_2H}/N_{\rm CH_3OH}$ ratio is lower by a factor of few or the order of magnitude in comparison with the Horsehead and Orion Bar PDRs. The ratio is similar to the value observed in hot corinos in the Perseus cloud. We conclude that ion-molecular and grain surface chemical routes rule the molecular abundances in the PDRs, and the PDRs inherit molecular abundances from the previous dark stage of molecular cloud evolution in spite of massive stars already emitting in optics. © 2021 The Author(s) Published by Oxford University Press on behalf of Royal Astronomical Society. Keywords: ASTROCHEMISTRYDUST, EXTINCTIONGALAXIES: STAR FORMATIONISM: MOLECULESPHOTODISSOCIATION REGION (PDR)RADIO LINES: ISM URI: http://hdl.handle.net/10995/111385 Access: info:eu-repo/semantics/openAccess SCOPUS ID: 85117157367 PURE ID: 23894512 ISSN: 0035-8711 DOI: 10.2495/SAFE210031 metadata.dc.description.sponsorship: This study is supported by the Russian Science Foundation, grant number 18-12-00351. This research has made use of NASA's Astrophysics Data System Bibliographic Services; SIMBADdatabase, operated atCDS, Strasbourg, France (Wenger et al. 2000); Aladin web page (Bonnarel et al. 2000); ASTROPY, a community-developed core PYTHON package for Astronomy (Astropy Collaboration et al. 2013); APLPY, an open-source plotting package for PYTHON (http://aplpy.github.com Robitaille & Bressert 2012). RSCF project card: 18-12-00351 Appears in Collections: Научные публикации, проиндексированные в SCOPUS и WoS CC

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