The PDR structure and kinematics around the compact H ii regions S235 A and S235 C with [C ii], [13C ii], [O i], and HCO+ line profiles
AuthorKirsanova, M S
Anderson, L D
Boley, P A
Bieging, J H
Pavlyuchenkov, Ya N
Samal, M R
Sobolev, A M
AffiliationUniv Arizona, Steward Observ
H II regions
ISM: kinematics and dynamics
photodissociation region (PDR)
MetadataShow full item record
PublisherOXFORD UNIV PRESS
CitationKirsanova, M. S., Ossenkopf-Okada, V., Anderson, L. D., Boley, P. A., Bieging, J. H., Pavlyuchenkov, Y. N., ... & Okada, Y. (2020). The PDR structure and kinematics around the compact H ii regions S235 A and S235 C with [C ii],[13C ii],[O i], and HCO+ line profiles. Monthly Notices of the Royal Astronomical Society, 497(3), 2651-2669.
Rights© 2020 The Author(s), Published by Oxford University Press on behalf of the Royal Astronomical Society.
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AbstractThe aim of this work is to study structure and gas kinematics in the photodissociation regions (PDRs) around the compact H II regions S235 A and S235 C. We observe the [C II], [C-13 II], and [O I] line emission, using SOFIA/upGREAT, and complement them by data of HCO+ and CO. We use the [C-13 II] line to measure the optical depth of the [C II] emission, and find that the [C II] line profiles are influenced by self-absorption, while the [C-13 II] line remains unaffected by these effects. Hence, for dense PDRs, [C-13 II] emission is a better tracer of gas kinematics. The optical depth of the [C II] line is up to 10 in S235 A. We find an expanding motion of the [C II]-emitting layer of the PDRs into the front molecular layer in both regions. Comparison of the gas and dust columns shows that gas components visible neither in the [C II] nor in low-J CO lines may contribute to the total column across S235 A. We test whether the observed properties of the PDRs match the predictions of spherical models of expanding H II region + PDR + molecular cloud. Integrated intensities of the [C-13 II], [C II], and [O I] lines are well represented by the model, but the models do not reproduce the double-peaked [C II] line profiles due to an insufficient column density of C+. The model predicts that the [O I] line could be a more reliable tracer of gas kinematics, but the foreground self-absorbing material does not allow using it in the considered regions.
VersionFinal published version
SponsorsRussian Science Foundation