大质量无星团块的证认与分析研究

The initial conditions of massive star formation still remain unclear. One of the obstacles is the rareness of massive starless clumps or cores. Galactic plane surveys using space and ground based facilities finished in the last decade give us a great opportunity to expand the sample. In this project, a brand new catalogue of massive starless clumps will be identified from more than 10000 dense condensations provided by the ATLASGAL survey based on mid-infrared to submillimeter observations. With the combination of data at 70-500 μm from the Hi-GAL project based on the Herschel Space Observatory, some fundamental properties, e.g. temperatures, densities, masses, and luminosities, will be revealed for a large sample of massive starless clump candidates. According to the initial inspections, more than 200 candidates have been included in the MALT90 survey, which mapped numerous dense clumps in 16 molecular lines using the Mopra telescope. On the bases of these data, chemical properties and kinematic features of some massive starless clumps will be well understood. ..This project will result in a relatively large number of massive starless clumps which can be used to carry out follow up observations. The increased number of massive starless clumps would boost the investigations of initial conditions of massive star formation. The uncovered physical and chemical features of sufficient massive starless clumps based on multiwavelength data and multi-transition observations in this project will help us constrain the initial conditions of massive star formation.

大质量无星团块或云核的稀缺为揭示大质量恒星形成初始状态带来困难。近年来的多个银道面巡天为相关研究提供了宝贵资源。本项目拟利用多波段测光数据从 ATLASGAL 项目给出的上万个致密团块中证认出一批具有较高可信度的大质量无星团块。结合 Hi-GAL 巡天提供的 70-500 微米远红外资料，对优选出的大质量无星团块的基本物理性质进行探究。预计新证认出的无星团块中有 200 余个被 MALT90 巡天所覆盖。这使得我们能够利用多谱线成图观测探究一批大质量无星团块的部分化学性质和运动学特征。本项目的执行将提供一批可用于探究大质量恒星形成初始状态的优良样品，为解决大质量无星团块或云核稀缺问题做出贡献；通过研究大质量无星团块的物理状态和部分化学性质，为揭示大质量恒星形成初始状态提供约束。

大质量无星团块的稀缺为揭示大质量恒星形成初始状态带来困难。近年来的多个银道面巡天为相关研究提供了宝贵资源。本项目利用多波段连续谱数据从 ATLASGAL 项目给出的上万个致密团块中证认出了463具有较高可信度的大质量无星团块。结合 HiGAL 和ATLASGAL巡天提供的 70-500 微米远红外及亚毫米波资料，对优选出的大质量无星团块的基本物理性质进行了探究。较低的温度和光度质量比，表明这批大质量无星团块是揭示大质量恒星形成初始状态的理想研究天体。在该项目支持下，完成首个Planck冷团块致密气体的巡天观测，发现Planck冷团块中的HCO+和HCN丰度显著低于经典恒星形成区。针对一例纤维-节点（filament-hub）结构进行的多波段观测研究揭示了分子云、分子团块和分子云核尺度上同时存在的物质下落，表明大质量无星云核可能并非形成大质量恒星形成的必备条件；在大质量恒星诞生的过程中，中心原恒星、致密分子云核及分子团块可以同时增长质量。项目执行期间，发表标注项目号的SCI学术论文11篇，其中第一标注文章6篇，项目主要成员第一作者文章5篇。研究成果超出预期。