The physics and chemistry of low-mass cores

低质量核心的物理和化学

• 批准号: 203356419
• 负责人: Dr. Amelia M. Stutz
• 金额: --
• 依托单位: Universidad de Concepción
• 依托单位国家: 德国
• 项目类别: Priority Programmes
• 财政年份: 2011
• 资助国家: 德国
• 起止时间: 2010-12-31 至 2014-12-31
• 项目状态: 已结题
• 来源: https://gepris.dfg.de/gepris/projekt/203356419?language=en
• 关键词: physics; chemistry; low; mass; cores

Low–mass molecular cloud cores are the birthplaces of solar–type stars. Therefore, a thorough understanding of star–formation requires detailed knowledge of their initial properties. Nearby, small and isolated clouds, like Bok globules, are ideal laboratories for studying the physical and chemical properties of such star–forming cores because they are free from the complicating effects present in more clustered star–forming regions and are relatively straight–forward to model. Despite this relative simplicity, we still lack robust measurements of two fundamental physical parameters of such cores: temperature and density. These two parameters regulate the chemical and dynamical evolution and the subsequent gravitational collapse and fragmentation. The data from our Herschel project “EPOS” allow us for the first time to directly measure the temperature and density structure in a sample of 14 isolated star–forming cores. In order to measure gas–grain coupling processes and the role of turbulence and magnetic support, we have already acquired a set of complementary molecular line maps of different CO isotopes and N2H+ and propose further observations of at least NH3, CS, HCO+. When combined, these observations present the unique opportunity to model, in an unprecedented way, the chemical and dynamical state of the densest and coldest star–forming units in the interstellar medium. Our aim is to derive a new — coherent — modeling approach in which the highly accurate physical structure derived from the dust continuum data serves as independent input for the state–of–the–art chemical models, which in turn allow us to constrain the chemical evolution of such star–forming cores.

低质量的分子云核心是太阳型恒星的诞生地。因此，要彻底了解恒星的形成，就需要对它们的初始性质有详细的了解。附近的小型孤立云，如博克球状体，是研究这类恒星形成核心的物理和化学性质的理想实验室，因为它们不受更密集的恒星形成区域中存在的复杂影响，并且相对直接建模。尽管相对简单，我们仍然缺乏对这种核心的两个基本物理参数的可靠测量：温度和密度。这两个参数控制着化学和动力学演化以及随后的引力坍缩和碎裂。来自我们的赫歇尔项目“EPOS”的数据使我们首次能够直接测量14个孤立恒星形成核心样本的温度和密度结构。为了测量气体-颗粒耦合过程以及湍流和磁支持的作用，我们已经获得了一组不同CO同位素和N2 H+的互补分子线图，并提出了至少NH3，CS，HCO+的进一步观测。当这些观测结合在一起时，就提供了一个独特的机会，以前所未有的方式模拟星际介质中致密和最冷的恒星形成单位的化学和动力学状态。我们的目标是获得一个新的相干建模方法，其中来自尘埃连续数据的高度准确的物理结构作为独立的输入，为国家的最先进的化学模型，这反过来又使我们能够约束这样的恒星形成的核心的化学演化。