Complete ATCA Census of High-Mass Clumps (CACHMC) Legacy Survey

The conversion of turbulent structures within molecular clouds into high-mass stars and star clusters, the relation between Galactic and extragalactic star formation, and the effects of Galactic environment on star formation are fundamentally important, yet unsolved problems in astrophysics. The two major theories for high-mass star formation are "competitive accretion" and "turbulent core accretion" (for review see Motte et al. 2018). These theories make distinct predictions about the initial conditions within star-forming clumps, and how the gas on approximately 1-pc "clump" scales affects the accretion history on the 0.05-pc "core" scales at which individual stars form. This survey targeted over 50 cold, high-mass dust clumps, making observations of the sites of all current and future Galactic high-mass star formation. Ammonia and methanol emission lines were observed, along with recombination lines and a masing water line. The data will be used to characterise the turbulent structure within the clumps and to directly measure the locations, temperatures, masses, temporal sequence, and kinematics of their individual ~0.05 pc size star-forming cores.

分子云内湍流结构向大质量恒星及星团的转化、银河系与河外星系恒星形成的关系，以及银河系环境对恒星形成的影响，是天体物理学中至关重要却尚未解决的基础问题。大质量恒星形成的两大主要理论为"竞争吸积"（competitive accretion）与"湍流核吸积"（turbulent core accretion）（综述参见Motte等2018）。这些理论对恒星形成团块内的初始条件，以及约1秒差距（parsec，缩写pc）尺度的"团块"气体如何影响单个恒星形成时0.05 pc尺度"核"上的吸积历史，做出了截然不同的预测。本巡天观测以50余个寒冷的大质量尘埃团块为目标，对银河系内所有当前及未来大质量恒星形成的区域进行了观测。观测对象包括氨与甲醇发射线，以及复合线和脉泽（maser）水线。这些数据将用于表征团块内的湍流结构，并直接测量其单个约0.05 pc大小的恒星形成核的位置、温度、质量、时间序列及运动学特征。