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What Controls Star Formation in Galaxies?

是什么控制着星系中恒星的形成？

基本信息

批准号：
1109395
负责人：
Mordecai-Mark Mac Low
金额：
$ 45.12万
依托单位：
American Museum Natural History
依托单位国家：
美国
项目类别：
Continuing Grant
财政年份：
2011
资助国家：
美国
起止时间：
2011-07-01 至 2017-06-30
项目状态：
已结题

来源：
https://www.nsf.gov/awardsearch/showAward?AWD_ID=1109395&HistoricalAwards=false
关键词：
What Controls Star Formation Galaxies

项目摘要

This investigation evaluates the relative importance different physical processes during molecular cloud and star formation. Overall, this improves our understanding of the dynamics of molecular cloud formation and of how external flows and internal massive star formation act to disperse or destroy them again. It tests whether star formation rates are governed by molecular cloud formation due to high pressure in a disk's mid-plane, or by gravitational instability of the combination of gas and stars. Related problems are the lifetimes and star formation efficiency in molecular clouds. Dr. Mac Low and his team use the FLASH adaptive mesh refinement (AMR) simulation code that can handle the modeling of the most important physical processes important to star formation models. These include effects of supernova explosions; self gravity; differential rotation in the shearing sheet approximation; ionizing, dissociating, and non-ionizing but heating radiation from point sources; magnetic fields; molecular chemistry in two different levels of approximation; an approximation to radiative cooling in optically thin and thick regions; a fixed stellar gravitational potential to maintain vertical stratification; the full galactic fountain; and sink particles emitting both radiation and stellar jets and winds. The models are done so that effects are integrated into a multiscale model of star formation covering scales ranging from 0.5 kiloparsec down to 100 Astronomical Units. The results help to distinguish between the "high midplane pressure" and the "gravitational instability" models. Thus, self-consistent numerical models follow the assembly of giant molecular clouds and the results of star formation within them. The team evaluates the relative importance of these processes by parameter studies using the fully resolved version of these models with full chemistry.This research program is an international collaboration between the Museum and the Institute for Theoretical Astrophysics of the University of Heidelberg. It will also support the training of a graduate student. Results from this research are also incorporated into the exhibition and education program of the American Museum of Natural History, including the Hayden Planetarium.

本研究评估了分子云和星星形成过程中不同物理过程的相对重要性。总的来说，这提高了我们对分子云形成的动力学以及外部流动和内部大质量星星形成如何再次分散或摧毁它们的理解。它测试了星星的形成速率是由圆盘中平面的高压导致的分子云形成所决定，还是由气体和恒星组合的引力不稳定性所决定。相关的问题是分子云中的寿命和星星形成效率。Mac Low博士和他的团队使用FLASH自适应网格细化（AMR）模拟代码，该代码可以处理对星星形成模型至关重要的最重要物理过程的建模。这些包括超新星爆炸的影响;自引力;剪切片近似下的差分旋转;电离、离解和非电离但加热的点源辐射;磁场;两种不同近似水平下的分子化学;光学薄和厚区域的辐射冷却近似;维持垂直分层的固定恒星引力势;完整的银河喷泉;下沉粒子会释放出辐射和恒星喷流和风。这些模型是这样做的，使影响被集成到一个多尺度模型的星星形成覆盖范围从0.5千秒差距到100天文单位。结果有助于区分“高中面压力”和“引力不稳定性”模型。因此，自洽的数值模型遵循巨大分子云的组装和其中星星形成的结果。该团队通过使用这些模型的完全解析版本和完全化学的参数研究来评估这些过程的相对重要性。该研究计划是博物馆和海德堡大学理论天体物理研究所之间的国际合作。它还将支持培训一名研究生。这项研究的结果也被纳入美国自然历史博物馆的展览和教育计划，包括海登天文馆。