THE DISTRIBUTION OF THE 62-61 AND 52-51 E-TYPE METHANOL MASERS IN OMC-1

被引:52
作者
JOHNSTON, KJ
GAUME, R
STOLOVY, S
WILSON, TL
WALMSLEY, CM
MENTEN, KM
机构
[1] MAX PLANCK INST RADIOASTRON,W-5300 BONN 1,GERMANY
[2] HARVARD SMITHSONIAN CTR ASTROPHYS,CAMBRIDGE,MA 02138
关键词
ISM; KINEMATICS AND DYNAMICS; MOLECULES; STRUCTURE; MASERS;
D O I
10.1086/170930
中图分类号
P1 [天文学];
学科分类号
0704 ;
摘要
The 6(2)-6(1) and 5(2)-5(1) E transitions of CH3OH have been mapped toward the Orion-KL region with an angular resolution of 3" and a frequency resolution of 12 kHz (= 0.15 km s-1). There are at least 16 masers of flux density greater than 3 Jy. These are distributed in a 40" long crescent shaped region, extending from NW to SE around the "hot core." The radial velocities and positions of some of these masers agree with a peak of the 8(0)-7(1) A transition of CH3OH, near 95 GHz. The most intense 6(2)-6(1) E maser is unresolved; the flux density of 103 Jy and size of less than 1".1 give a brightness temperature of greater than 10(5) K. The FWHP line widths, including the instrumental resolution, range from less than 0.15 km s-1 (unresolved) to 1 km s-1. What have been previously cataloged as spatially extended individual masers are most likely blends of maser components with slightly different radial velocities. The E-type masers in Orion appear to cluster on scale sizes of less than 3". From a multiline analysis and our limits to maser source sizes, the column densities in the regions with the most intense lines are greater than 2 x 10(22) cm-2. The spatial distribution and the observed velocities suggest that the methanol masers arise from high column density gas-adjacent to the Hot Core. The masers may be located very near the interface of the high-velocity outflow and the surrounding dense gas.
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页码:232 / 239
页数:8
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