The detection of new methanol masers in the 5(-1)-4(0)E line

Forty-eight objects were detected in the 5(-1)(-4)0(E) methanol line at 83. 5 GHz during a survey of Class I maser sources. Narrow maser features were found in 14 of these. Broad quasi-thermal lines were detected toward other sources. One of the objects with narrow features at 84.5 GHz, the young bip olar outflow L1157, was also observed in the 8(0)-7(1)A(+) line at 95.2 GHz : a narrow line was detected at this frequency. Analysis showed that the br oad lines are usually inverted. The quasi-thermal profiles imply that there are no more than a few line opacities. These results confirm the plausibil ity of models in which compact Class I masers appear in extended sources as a result of a preferential velocity field. (C) 2001 MAIK "Nauka/Interperio dica".