Modeling the three-dimensional structure and dynamics of the corona of the Sun and stars

模拟太阳和恒星日冕的三维结构和动力学

• 批准号: 17546268
• 负责人: Professor Dr. Hardi Peter
• 金额: --
• 依托单位: Max-Planck-Institut für Sonnensystemforschung (MPS)
• 依托单位国家: 德国
• 项目类别: Research Grants
• 财政年份: 2005
• 资助国家: 德国
• 起止时间: 2004-12-31 至 2011-12-31
• 项目状态: 已结题
• 来源: https://gepris.dfg.de/gepris/projekt/17546268?language=en
• 关键词: Modeling; three; dimensional; structure; dynamics

A cool star like our Sun is surrounded by an outer atmosphere, the corona, which is a hundred times hotter than its surface ¿ still being an unsolved puzzle. Among other heating processes it was suggested that the magnetic field lines in the corona are braided by motions on the stellar surface. The subsequent dissipation of the induced currents leads to efficient heating of the corona up to a million degrees. The progress in computer power now allows us to study the corona by means of three-dimensional time-dependent models of the fluid dynamics including magnetic fields. Our simulations are coupled with a synthesis of extreme ultraviolet emission line spectra, which is essential for a detailed comparison to observations. These models will be the first to account for the complex interaction of regions with strong and weak magnetic fields, allowing for an investigation of the 3D structure and dynamics of the low corona. If our preliminary results will be substantiated, we can provide ample evidence that the field line braiding indeed is the dominant heating mechanism, which would be a large step forward in understanding coronal heating. Our results will also have impact on the study of hot magnetically heated plasmas in other astrophysical objects, like accretion disks surrounding a newly formed star with its (potential) planets. Furthermore, the solar corona as being the source of the extreme ultraviolet radiation, is of interest for the chemistry of the upper Earth s atmosphere.

像我们的太阳这样的冷星星被外层大气-日冕所包围，日冕比它的表面热一百倍-仍然是一个未解的谜。在其他加热过程中，有人认为日冕中的磁力线是由恒星表面的运动编织而成的。感应电流的随后消散导致日冕的有效加热高达一百万度。计算机能力的进步现在允许我们通过三维时间依赖的流体动力学模型（包括磁场）来研究日冕。我们的模拟加上极紫外发射线光谱的合成，这是必不可少的详细比较观测。这些模型将是第一个解释强磁场和弱磁场区域复杂相互作用的模型，从而可以研究低日冕的三维结构和动力学。如果我们的初步结果得到证实，我们可以提供充分的证据，证明磁力线编织确实是主要的加热机制，这将是理解日冕加热的一大步。我们的结果也将对其他天体中的热磁加热等离子体的研究产生影响，例如围绕新形成的星星及其（潜在的）行星的吸积盘。此外，日冕作为极紫外线辐射的来源，对地球上层大气的化学很感兴趣。