Dynamics of Accretion Disks around Magnetized Stars

磁化恒星周围吸积盘的动力学

• 批准号: 1008636
• 负责人: Richard Lovelace
• 金额: $ 31.75万
• 依托单位: Cornell University
• 依托单位国家: 美国
• 项目类别: Continuing Grant
• 财政年份: 2010
• 资助国家: 美国
• 起止时间: 2010-09-15 至 2013-08-31
• 项目状态: 已结题
• 来源: https://www.nsf.gov/awardsearch/showAward?AWD_ID=1008636&HistoricalAwards=false
• 关键词: Dynamics; Accretion; Disks; around; Magnetized

Accreting magnetized stars, such as Classical T Tauri stars (CTTSs), cataclysmic variables, and X-ray pulsars may have dynamically important magnetic fields that can disrupt the accretion disk. Prior NSF-supported pioneering simulations have shown that accreting magnetized stars may be in stable or unstable regimes of accretion with different observational properties (ordered or stochastic light-curves). If the disk comes close to the star, it interacts through the boundary layer, where simulations have shown Kelvin-Helmholtz-type instabilities. Although these simulations and associated theoretical analyses show many interesting features which could be compared with observation, there is a need further to investigate the disk-magnetosphere/disk-star interaction, including the possibility of some type of Magneto-Rotational Instability (MRI). This new project includes simulations of the disk-magnetosphere interaction specifically tailored with 2.5D and 3D Godunov-type codes to model MRI-driven accretion in relatively thin disks. Associated theoretical analysis will give a deeper understanding of different types of instabilities at the disk-magnetosphere/disk-star boundaries. Because CTTSs show multiple variability features in rotation timescales, theirs are the photometric and spectral light-curves that will be compared with simulations. Spectrum modeling will use a 3D Monte Carlo radiative transfer code. This study will 1) investigate MRI-driven accretion onto a magnetized star; 2) investigate, theoretically and numerically, different instabilities at the disk-magnetosphere and disk-star boundaries; and 3) compare simulated light-curves and spectra with those observed in different CTTSs.The results will apply to different magnetized stars, including the CTTSs, cataclysmic variables, accreting brown dwarfs and accreting neutron stars. The research will provide a salutary example of comparing state-of-the-art 2.5D and 3D models of magnetized stars with the best available observations. The project will train undergraduate and graduate students and a postdoctoral research associate in this modern area of multidimensional magneto-hydrodynamics. Results will be included in lectures to undergraduate students, to school students, and to Cornell's public visitors. Animated visualizations have recently been developed and will be used in various talks. The team also supports an exhibit in the Tompkins County Science Museum.

吸收磁化的恒星，例如经典的T Tauri恒星（CTTS），灾难性变量和X射线脉冲星，可能具有动态重要的磁场，可以破坏吸积盘。 先前的NSF支持的开拓性模拟表明，具有不同观察性能（有序或随机的光曲线）的吸收恒星可能处于稳定或不稳定的增值状态。 如果磁盘靠近恒星，则它通过边界层相互作用，在该边界层中，模拟显示了kelvin-helmholtz-type的不稳定性。 尽管这些模拟和相关的理论分析显示了许多有趣的特征，这些特征可以与观察结果进行比较，但仍需要进一步研究磁盘 - 磁层/磁盘-STR-StAR相互作用，包括某种类型的磁性旋转不稳定的可能性（MRI）。 这个新项目包括对专门针对2.5D和3D Godunov型代码量身定制的磁盘 - 磁层相互作用的模拟，以模拟相对较薄的磁盘中的MRI驱动积聚。 相关的理论分析将使对磁盘/磁盘星界的不同类型的不稳定性有更深入的了解。 由于CTTS在旋转时间标准中显示出多种变异性特征，因此它们的光度和光谱曲线将与模拟进行比较。 频谱建模将使用3D蒙特卡洛辐射传输代码。 这项研究将1）研究MRI驱动的积聚到磁化恒星上； 2）从理论和数字上研究磁盘层和磁盘星界的不同不稳定性； 3）将模拟的光曲线和光谱与在不同CTTS中观察到的模拟曲线和光谱进行比较。结果将适用于不同的磁化恒星，包括CTTS，灾难性变量，吸收棕色矮人和积聚中子星。 这项研究将提供一个有益的例子，即将磁化恒星的最先进的2.5D和3D模型与最佳可用观测值进行比较。 该项目将培训本科生和研究生，并在这个现代的多维磁湿动力学领域的博士后研究助理。 结果将包括在本科生，学校学生以及康奈尔公共访客的讲座中。 最近开发了动画可视化，并将用于各种演讲。 该团队还支持汤普金斯县科学博物馆的展览。