Understanding the Reversals in Polarity of the Magnetic Fields of Planets and Stars

了解行星和恒星磁场极性的反转

• 批准号: 1743852
• 负责人: Michael Calkins
• 金额: $ 29万
• 依托单位: University of Colorado at Boulder
• 依托单位国家: 美国
• 项目类别: Standard Grant
• 财政年份: 2018
• 资助国家: 美国
• 起止时间: 2018-02-15 至 2022-12-31
• 项目状态: 已结题
• 来源: https://www.nsf.gov/awardsearch/showAward?AWD_ID=1743852&HistoricalAwards=false
• 关键词: Understanding; Reversals; Polarity; Magnetic; Fields

Magnetic fields in the stars and planets are common features in the universe. The individual properties of these magnetic fields vary widely, however, among all of these different objects. In our own Solar System, the Sun's magnetic field has a well-defined, periodic reversal of polarity every 22 years. In contrast, the Earth undergoes magnetic field polarity reversals that are irregular in timing. All planets in the Solar System except Mars and Venus have active magnetic fields, and Mars was once home to a relatively strong magnetic field. Magnetic fields have also been observed in other stars. Research into the causes of magnetic field polarity reversals can produce results affecting the forecasting of solar flares, as well as understanding the space environment that will affect human exploration beyond the Earth's orbit. The investigators will develop and use new software tools to advance our understanding of polarity reversals. The Principal Investigator and a graduate student will lead this project, which will also make many opportunities for undergraduates to join in the research.The investigators will develop novel dynamo modeling analysis tools and incorporate them into a well-understood and highly efficient magnetohydrodynamic code to advance our understanding of polarity reversals in new dynamical regimes. These tools will allow for a multiscale analysis of polarity reversals, and enable a precise characterization of the physical processes at work in the two reversal regimes observed to date. This research has the potential to significantly alter the current view of dynamo physics by conducting one of the most detailed numerical analyses to date of the equations governing natural dynamos.

恒星和行星中的磁场是宇宙中的共同特征。 然而，在所有这些不同的物体中，这些磁场的个体属性差异很大。在我们自己的太阳系中，太阳的磁场每22年有一个明确的周期性极性反转。 与此相反，地球经历磁场极性反转，这是不规则的时间。 除了火星和金星之外，太阳系中的所有行星都有活跃的磁场，火星曾经是一个相对较强的磁场所在地。 在其他恒星中也观察到了磁场。 对磁场极性逆转原因的研究可产生影响太阳耀斑预测的结果，并有助于了解将影响人类在地球轨道以外进行探索的空间环境。 研究人员将开发和使用新的软件工具，以促进我们对极性逆转的理解。 主要研究员和一名研究生将领导这个项目，这也将为本科生提供许多参与研究的机会。研究人员将开发新的发电机建模分析工具，并将其纳入一个易于理解和高效的磁流体动力学代码，以促进我们对新动力学机制中极性反转的理解。这些工具将允许对极性反转进行多尺度分析，并能够精确描述迄今观察到的两种反转机制中的物理过程。这项研究有可能通过对自然发电机方程进行迄今为止最详细的数值分析，显着改变目前对发电机物理学的看法。

项目成果

Asymptotic behaviour of rotating convection-driven dynamos in the plane layer geometry

平面层几何中旋转对流驱动发电机的渐近行为

• DOI: 10.1017/jfm.2022.848
• 发表时间: 2022
• 期刊: Journal of Fluid Mechanics
• 影响因子: 3.7
• 作者: Yan, Ming;Calkins, Michael A.
• 通讯作者: Calkins, Michael A.

Quasistatic magnetoconvection with a tilted magnetic field

具有倾斜磁场的准静态磁对流

• DOI: 10.1103/physrevfluids.7.043504
• 发表时间: 2022
• 期刊: Physical Review Fluids
• 影响因子: 2.7
• 作者: Nicoski, Justin A.;Yan, Ming;Calkins, Michael A.
• 通讯作者: Calkins, Michael A.

Large-scale magnetic field saturation and the Elsasser number in rotating spherical dynamo models

旋转球形发电机模型中的大尺度磁场饱和和 Elsasser 数

• DOI: 10.1093/mnrasl/slab097
• 发表时间: 2021
• 期刊: Monthly Notices of the Royal Astronomical Society: Letters
• 作者: Orvedahl, Ryan J;Featherstone, Nicholas A;Calkins, Michael A
• 通讯作者: Calkins, Michael A

Prandtl-number Effects in High-Rayleigh-number Spherical Convection

高瑞利数球形对流中的普朗特数效应

• DOI: 10.3847/1538-4357/aaaeb5
• 发表时间: 2018
• 期刊: The Astrophysical Journal
• 作者: Orvedahl, Ryan J.;Calkins, Michael A.;Featherstone, Nicholas A.;Hindman, Bradley W.
• 通讯作者: Hindman, Bradley W.

Strong large scale magnetic fields in rotating convection-driven dynamos: The important role of magnetic diffusion

旋转对流驱动发电机中的强大规模磁场：磁扩散的重要作用

• DOI: 10.1103/physrevresearch.4.l012026
• 发表时间: 2022
• 期刊: Physical Review Research
• 影响因子: 4.2
• 作者: Yan, Ming;Calkins, Michael A.
• 通讯作者: Calkins, Michael A.