How the Milky Way ticks: comprehending complexity in the interstellar medium, from ethereal wisps to dense structures at the onset of star formation

银河系如何运行：理解星际介质的复杂性，从空灵的缕缕到恒星形成开始时的致密结构

• 批准号: 6843-2013
• 负责人: Martin, Peter
• 金额: $ 3.79万
• 依托单位: University of Toronto
• 依托单位国家: 加拿大
• 项目类别: Discovery Grants Program - Individual
• 财政年份: 2013
• 资助国家: 加拿大
• 起止时间: 2013-01-01 至 2014-12-31
• 项目状态: 已结题
• 来源: https://www.nserc-crsng.gc.ca/ase-oro/Details-Detailles_eng.asp?id=520967
• 关键词: How; Milky; Way; ticks; comprehending

I want to understand how our Milky Way Galaxy ticks, why, unlike in other galaxies, there is still an interstellar medium (ISM) in which stars are continually forming. This requires a broad program to understand Galactic ecology, the cycling of the ISM from the diffuse atomic phase to dense molecular clouds, the sites of star formation, and back. So complex is the ISM that comprehending the structure and dynamics at the key stages, from ethereal wisps to dense structures at the onset of star formation, requires exploitation and synthesis of all available multiwavelength data. I am working with international teams at a new frontier revolutionizing this field, in the submillimetre with the Herschel and Planck satellites which image thermal emission by small interstellar dust particles tracing the gas. Deciphering the fascinating evolution of dust becomes necessary because dust is implicated in so many key interstellar processes. An exciting new insight from Planck is polarization, probing the important role of the interstellar magnetic field in the life cycle. A key question that will be addressed is the state of the ISM in the hitherto elusive earliest stages of star formation, before substantial accretion and nuclear ignition reveal new stars. The compact structures that we can now detect in the submillimetre are cold condensations, starless cores. How these form and the dependence on environment are still unkown, but progess can be made by relating the onset and efficiency of core formation, and their mass function, to the larger-scale high column density structures like filaments, and tracing the thermal and dynamical state with molecular line probes. At high Galactic latitudes we see the return cycle, the interstellar cirrus, fairly local gas and dust in the disk, as well as intermediate velocity clouds, part of the Galactic fountain, material thrust out of the disk and circulating in the halo. Comprehending the turbulent structure of the cirrus is essential to learning how molecular clouds form, and has another huge impact because cirrus is a polarized foreground that must be removed to reach the cosmological goals of studies of the cosmic microwave and infrared backgrounds.

我想了解我们银河系的tick虫是如何的，为什么与其他星系不同，仍然有一个星际介质（ISM），其中恒星不断形成。 这需要一个广泛的程序来了解银河生态学，即从弥漫性原子相循环到密集的分子云，恒星形成的位置和背部。 ISM如此复杂，以至于在关键阶段中理解从空灵的WISP到恒星形成开始时的密集结构的结构和动力学，就需要对所有可用的多波长数据进行开发和综合。 我正在与国际团队合作，在一个新的边境革新这一领域，在赫尔谢尔和普朗克卫星的亚军上，这些卫星会通过追踪气体的小星际灰尘颗粒来对热发射。 破译尘埃的迷人演变变得必要，因为灰尘与许多关键的星际过程有关。 波兰克的一个令人兴奋的新见解是极化，探测了星际磁场在生命周期中的重要作用。 将要解决的一个关键问题是迄今为止恒星形成最早难以捉摸的阶段的ISM状态，然后在大量积聚和核点火揭示了新的恒星。 我们现在可以在亚亚毫米仪中检测到的紧凑结构是冷凝结，无星核。 这些形式和对环境的依赖性如何仍然不镇压，但是可以通过将核心形成的发作和效率与较大规模的高柱密度结构（如细丝）以及将热和动态状态与分子线探针相关联。 在高银河纬度处，我们看到了回流周期，星际卷心，磁盘中的相当局部气体和灰尘以及中间速度云，银河喷泉的一部分，材料从磁盘上推出并在光环中循环。 理解卷曲的湍流结构对于学习分子云的形成至关重要，并且具有另一个巨大的影响，因为卷心是一个极化的前景，必须去除宇宙微波和红外背景的研究的宇宙学目标。