The G 1,6-0,025 giant molecular cloud consists of dumps with sizes varying from 3'' (0,1 pc) to 5' (10 pc). Column densities of hydrogen and methanol in the large clumps are about (1-4) . 10(23) and (1-2) . 10(15) cm-2 respectively. Hydrogen densities in the large clumps vary from 10(2) to 5 . 10(4) cm-3 and in the small clumps reach values > 10(6) cm-3. A high kinetic temperature in the cloud, T(k) > 50-100 K, is partially a consequence of collisions with individual clumps. Such a collision is probably occuring nowadays toward (17h46m12s, -27 33'15'') where a 165 km/s clump is observed. Shocks connected with this collision can lead to enhancement of methanol abundance in some small-scale clumps with masses greater-than-or-equal-to 70-300 M. which therefore manifest spike features in the 4-1-3(0)E line. This enhancement results from chemical reactions initiated by the methanol evaporation from the grain mantles. A probable protostar cluster is present in the same direction. This fact can be a consequence of the collision too. Sensitivity of a set of methanol lines to the values of physical parameters is considered on the basis of statistical equilibrium calculations. It is shown that further methanol observations will bring us to a better understanding of the status of giant molecular clouds.

Original languageRussian
Pages (from-to)1148-1165
Number of pages18
JournalАстрономический журнал
Volume69
Issue number6
Publication statusPublished - 1992

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  • Astronomy & Astrophysics

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