Magnetohydrodynamics of stellar interiors

奖项编号：AST-0607495PI: Pascale garau机构：加州大学圣克鲁斯分校标题：恒星内部磁流体动力学摘要这项研究是一个长期项目的一部分，旨在更好地了解恒星内部的磁流体动力学。为此，构建了包含大尺度磁场与流相互作用的二维动态结构和进化代码。小尺度场和流的影响也通过湍流闭合来模拟。在这里，PI将继续开发数值算法（该算法已经产生了有关太阳辐射区域动力学的结果）并测试闭合模型（该模型已经成功地通过旋转剪切流的实验数据进行了测试）。具体任务包括：1)发展计算方法，将数值结果外推到各种扩散参数的太阳值，并根据太阳观测结果进行检验。2)进一步改进和扩展现有的闭合模型，考虑湍流能量输运，并对模型的预测结果进行旋转对流三维数值模拟的验证。3)将辐射区模型与湍流封闭模型相结合，得到了完整的用于研究太阳型恒星内部磁流体动力学的数值算法，并得到了恒星各种参数（结构、内部场强、自转速率）的定性结果。未来计划的工作将依次调查：获得各种轴对称和非轴对称不稳定性的模型的稳定性；模型对磁循环产生的动力学行为；以及与各种来源的现有数据（例如星震学、多普勒成像、威尔逊山钙线测量）进行仔细的定量比较。正在开发的建模方法将包括动力学的几何方面（缺少1D模型），而不需要3D模型的繁重计算负载。因此，这里的工作将对天文学的许多其他领域有价值——特别是星震学和太阳内部研究，在这些领域，观测的复杂性现在需要更好的模型。因此，一旦完全开发，这些工具将提供给天文学界。这项工作还支持一名研究生，他将接受数值磁流体动力学建模的培训，并将这些结果与观测结果进行解释/比较。

AWARD NO: AST-0607495PI: Pascale GaraudINSTITUTION: University of California Santa CruzTITLE: Magnetohydrodynamics of stellar interiorsABSTRACTThis research is part of a long-term project to better understand the magnetohydrodynamicsof stellar interiors. Towards this end, a 2-dimensional dynamical structureand evolution code is being constructed which incorporates the interaction between largescalemagnetic fields and flows. The effects of small scale fields and flows are alsomodeled through turbulence closure. Here the PI will continue developing the corenumerical algorithm (which is already producing results concerning the dynamics of thesolar radiative region) and testing the closure model (which has been successfully testedagainst experimental data for rotating shear flows). Specific tasks to be undertakeninclude: 1) Developing computational methods to extrapolate numerical results to solarvalues of the various diffusion parameters and testing them against solar observations. 2)Further improving and extending the existing closure model to take into account turbulentenergy transport and testing the model predictions against 3D numerical simulations ofrotating convection. And 3) combining the radiative zone model with the turbulenceclosure model to obtain a complete numerical algorithm designed to study the magnetohydrodynamicsof the interior of a solar type star, and obtaining qualitative results for avariety of stellar parameters (structure, internal field strength, rotation rate). Futureplanned work will then investigate in turn: the stability of the models obtained to variouskinds of axially symmetric and non-axially symmetric instabilities; the dynamicalbehavior of the model with respect to the generation of a magnetic cycle; and the carefulquantitative comparison with existing data from various sources (e.g. asteroseismology,Doppler Imaging, Mount Wilson Ca-line survey).The modeling approach being developed will include geometric aspects of the dynamics(missing from 1D models) without the heavy computational load of 3D models. Thus thework here will be of value to many other areas of astronomy - particularlyasteroseismology and studies of the solar interior where the sophistication of theobservations now demand better models. Therefore, once fully developed, these tools willbe made available to the astronomical community. This work also supports a graduatestudent who will be trained in numerical magnetohydrodynamic modeling andinterpreting/comparing these results with observations.