Sgr B2中处于振动激发态的CH_3CN分子

VIBRATIONALLY EXCITED CH_3CN IN Sgr B_2

使用BIMA的C位形混合波寻联结9元天线阵，对SgrB2（N）和SgrB2（M）观测了CH3CN分子振动激发态v8＝1的6k－5k线系.仅在SgrB2（N）的10＂×14＂区域里探测到上述发射线．在8．5kpe的距离下，该区域的相应线尺寸是0．41pc×0．58pc．对于SgrB2（M）没有探测到高于均方根噪音的发射流量密度．经粗略地估计，SgrB2（N）区的振动激发温度约为300K．针对此线系的激发机制以及SgrB2（N）区和SgrB2（M）区物理条件之间的差别进行了讨论．

The line series CH3CN is observed toward Sgr B2(N) and SgrB2(M) with hybrid - C configurations of the 9 - element BIMA array. The emissionis detected only in a 10' x 14' region of Sgr B2(N) cormsponding to 0.41pc× 0.58pcat the distance of 8.5kpc. No emission of flux densities higher than rms noise isdetected toward Sgr B2(M). The vibrational excitation temperature could be roughlyestimated as 300K. The excitation mechanism of the line series and the differencesbetWeen Sgr B2(N) and Sgr B2(M) are discussed.