Physical and evolutionary status of G1.6–0.025 giant molecular cloud as revealed by 4−1-3OE methanol weak maser

  • A. M. Sobolev
8. Methanol Masers in Star Forming Regions
Part of the Lecture Notes in Physics book series (LNP, volume 412)


G1.6 giant molecular cloud consists of the clumps 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)x1023 and (1+2)x1015 cm−2 correspondingly. Hydrogen densities in the large clumps vary from 102 to 5x104 cm−3 and in the small clumps reach the values > 106 cm−3. High kinetic temperature in the cloud TK> 50+100 K partially is a consequence of collisions with individual clumps. Such collision probably occurs nowadays toward (α=17h46m12s,δ=-27o33′15″), where the 165 km/s clump is observed.

Shocks connected with this collision can lead to enhancement of methanol abundance in some clumps with masses 70+300 MΘ and sizes about 3″ (4x1017 cm ), which therefore manifestspikefeatures in 4−1-3OE line. This enhancement is the result of chemical reactions initiated by the methanol evaporation from grain mantles.

A probable protostar cluster is present in the same direction.


Column Density Hydrogen Density Small Clump Large Clump Methanol Evaporation 
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Copyright information

© Springer-Verlag 1993

Authors and Affiliations

  • A. M. Sobolev
    • 1
  1. 1.Astronomical ObservatoryUrals State UniversityEkaterinburghRussia

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