To understand the origin of the CH3OH maser emission, we map the distribution and excitation of the thermal CH3OH emission in a sample of 14 relatively nearby (OH emission in a sample of 14 relatively nearby (3OH emission is compact and confined to a region OH emission is compact and confined to a region OH emission is compact and confined to a region 3OH maser emission. Four sources have more extended thermal CH3OH emission without a clear peak, and for the remaining two sources, the emission is too weak to map. The compact sources have linear velocity gradients along the semi-major axis of the emission of 0.3 - 13 kms-1 pc-1. The rotation diagram analysis shows that in general the highest rotation temperature is found close to the maser position. The confined and centrally peaked CH3OH emission in the compact sources indicates a single source for the CH3OH gas and the velocity fields show signs of outflow in all but one of the sources. The high detection rate of the torsionally excited v t = 1 line and signs of high-K lines at the maser position indicate radiative pumping, though the general lack of measurable beam dilution effects may mean that the masing gas is not sampled well and originates in a very small region.
|Titel||Cosmic Masers - from OH to H0|
|Subtitel||Proceedings of the International Astronomical Union|
|Redacteuren||R.S. Booth, E.M.L. Humphreys, W.H.T. Vlemmings|
|Status||Published - jul.-2012|