Detection of a New Methanol Maser Line with the Kitt Peak 12 Meter Telescope by Remote Observing from Moscow

摘要

A new methanol maser line 6_(-2)5_0 E at 133 GHz was detected with the 12 m Kitt Peak radio telescope using a remote observation mode from Moscow. Moderately strong, narrow maser lines were found in DR 21(OH), DR 21-W, OMC-2, M8E, NGC 2264, L379, and W33-Met. The masers have similar spectral features in other transitions of methanol E at 36 and 84 GHz and in transitions of methanol A at 44 and 95 GHz. All these are class I transitions, and the new masers also belong to class I. In two other methanol transitions near 133 GHz, 5_(-2)6_(-1) E and 6_27_1 A+, only thermal emission was detected in some sources. Several other sources with wider lines in the transition 6_(-1)5_0 E also may be masers, since they do not show any emission at the two other methanol transitions near 133 GHz. These are NGC 2071, S231, S255, and GGD 27, also known as class I masers. The ratio of intensities and line widths of the 133 GHz masers and 44 GHz masers is consistent with the saturated maser model, in which the line rebroadening with respect to unsaturated masers is suppressed by cross-relaxation due to elastic collisions.