银心附近高速度弥散云观测研究

Bania's Clump 2 (located at L=3-3.5 deg) and the complex located at L=5.5 deg exhibit the most prominent high-velocity dispersions (>150 km/s) of all Galactic molecular complexes, but show little/no star formation. Therefore, they provide exceptional locations to test the turbulent heating hypothesis. Formaldehyde (H2CO) and ammonia (NH3), molecules which trace the dense molecular gas, have been proven to be excellent tracers for estimates of the kinetic temperature of dense molecular clouds. We propose to observe the transitions of H2CO (4-3) and the metastable inversion transitions of NH3 (1,1)-(7,7) toward Bania's Clump 2 and the L=5.5 deg complex: (1) to obtain the gas kinetic temperatures and temperature structures of dense clumps, (2) to compare these results with those obtained from dust, (3) to seek for links between kinetic temperature and gas heating mechanisms (e.g., turbulence, radiation), and (4) to reveal whether high temperatures are responsible for suppressing star formation.

Bania’s Clump 2 (位于L=3°-3.5°)和L=5.5°复合体在整个银河系的分子云复合体中拥有最强的速度弥散（>150 km/s），但其中似乎没有（或很弱）的恒星形成活动。因此，它们提供了非常理想的场所来验证气体湍流加热理论。甲醛和氨分子都是致密气体探针，曾被证实是非常理想的致密分子云温度计。本项目计划观测研究Bania’s Clump 2和L=5.5°复合体中的H2CO(4-3)和NH3(1,1)-(7,7)跃迁：（1）测量致密团块的温度和温度结构；（2）对比研究气体和尘埃温度的关系；（3）探寻温度和气体加热机制（例如，湍流，辐射）的关系；（4）揭示高温是否抑制致密团块中的恒星形成活动。

使用国内外多台射电望远镜，结合国际上红外和射电波段巡天数据，研究了银心附近高速度弥散云以及大麦哲伦星云和银河系中的多个大质量恒星形成区物理和化学性质：（1）用氨分子的多条跃迁研究了L = 5.5°复合体中致密气体的温度、气体温度和尘埃温度关系、气体的加热、以及氨分子丰度的演化；（2）用HCN/HNC分子研究了L = 1.3°复合体的温度结构及气体加热；（3）用甲醛、氨和硫甲醛分子研究了大麦哲伦星云和银河系中的多个大质量恒星形成区中致密气体的加热;（4）探讨了激波、机械运动和湍流活动对致密气体的加热；（5）揭示了高温和强烈的激波活动对恒星形成的影响。