title: Density structure of the Sgr B2 molecular cloud probed by low-J lines of CS.
abstract: We have observed the CS (2-1) and (3-2), and 13CS (2-1) transitions toward the Galactic Center molecular cloud Sgr B2 which consists of several clumps with different chemical properties. We have newly identified a cloud at 30 km s-1 from a CS (2-1) optical depth map. This cloud lies 1.5' South from the Sgr B2 (M) position and has a diameter of approximately 2.5 pc and a total column density of 7 x 10(23) cm-2 assuming optically thin emission of the 13CS (2-1) line. Towards the 2'N Cloud no evidence for a density enhancement is found, which suggests that the strong emission from HNCO and HCO+2 is due to chemical effects. The main isotopic CS lines show broad wing components similar to previous studies, but we find rotational temperatures Trot(CS) < 10 K at this region.
authors.affiliation: Korea Astronomy Observatory, Hwaam, Yusong, Korea.
authors.forename: Y C
authors.initials: YC
authors.lastname: Minh
authors.forename: A
authors.initials: A
authors.lastname: Hjalmarson
mesh_terms: D001256:Astronomy / Q000295:instrumentation; D002244:Carbon / Q000032:analysis*; D002247:Carbon Isotopes; D005118:Extraterrestrial Environment; D013057:Spectrum Analysis; D013455:Sulfur / Q000032:analysis*; D013696:Temperature
chemical_list: D002247:Carbon Isotopes; D013455:Sulfur; D002244:Carbon