论文标题
观察和分析吸收线，包括J = k的CH3CN旋转水平：Sagittarius B2（M）的包膜
Observations and Analysis of Absorption Lines including J = K Rotational Levels of CH3CN: The Envelope of Sagittarius B2(M)
论文作者
论文摘要
散布和半透明云中的分子由于辐射和碰撞引起的激发而经历冷却。但是，围绕乙腈分子轴CH3CN的旋转无法通过辐射冷却，从而导致旋转种群在J = K水平上浓缩。我们旨在搜索具有差异和半透明云中J = K水平浓度的CH3CN的吸收线。使用Nobeyama 45 m望远镜调查了GAL = 73.6 GHz的JK = 43-33的转变。根据检测到的吸收线向SGR B2（M），辐射温度为2.8 +/- 0.5 K，动力学温度为88 +/- 29 K，柱密度为（1.35 +/- 0.14）X 10^14 CM-2为这种分子得出，这是该分子的极高浓度J = K =较高的启发温度和较高的降压温度。吸收线在64 km S-1的速度下发生。结果证实，SGR B2（M）的包膜中存在J = K水平浓度的CH3CN。
Molecules in diffuse and translucent clouds experience cooling as a result of radiation and less excitation from collisions. However, a rotation around a molecular axis of acetonitrile, CH3CN, cannot be cooled by radiation, causing rotational populations to concentrate at the J = K levels. We aim to search for absorption lines of CH3CN having J = K level concentrations in diffuse and translucent clouds. The JK = 43-33 transition at 73.6 GHz was investigated toward Sgr B2(M) in the Galactic Center region and other sources, using the Nobeyama 45 m telescope. Based on the detected absorption lines toward Sgr B2(M), a radiation temperature of 2.8 +/- 0.5 K, kinetic temperature of 88 +/- 29 K, and column density of (1.35 +/- 0.14) x 10^14 cm-2 were derived for this molecule, revealing extremely concentrated J = K levels due to the lower excitation temperature and the higher kinetic temperature. The absorption lines occurred at a velocity of 64 km s-1. The results confirm that CH3CN with J = K level concentrations exists in the envelope of Sgr B2(M).
