title: Observations of chemical differentiation in clumpy molecular clouds.
abstract: We have extensively mapped a sample of dense molecular clouds (L1512, TMC-1C, L1262, Per7, L1389, L1251E) in lines of HC3N, CH3OH, SO and C18O. We demonstrate that a high degree of chemical differentiation is present in all of the observed clouds. We analyse the molecular maps for each cloud, demonstrating a systematic chemical differentiation across the sample, which we relate to the evolutionary state of the cloud. We relate our observations to the cloud physical, kinematical and evolutionary properties, and also compare them to the predictions of simple chemical models. The implications of this work for understanding the origin of the clumpy structures and chemical differentiation observed in dense clouds are discussed.
authors.affiliation: Astrophysics Group, Cavendish Laboratory, J. J. Thomson Avenue, Cambridge, UK. j.buckle@mrao.cam.ac.uk
authors.forename: Jane V
authors.initials: JV
authors.lastname: Buckle
authors.forename: Steven D
authors.initials: SD
authors.lastname: Rodgers
authors.forename: Eva S
authors.initials: ES
authors.lastname: Wirström
authors.forename: Steven B
authors.initials: SB
authors.lastname: Charnley
authors.forename: Andrew J
authors.initials: AJ
authors.lastname: Markwick-Kemper
authors.forename: Harold M
authors.initials: HM
authors.lastname: Butner
authors.forename: Shigehisa
authors.initials: S
authors.lastname: Takakuwa