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.

吸积的磁化星，如经典金牛T星（CTTS）、激变变星和X射线双星可能具有动态重要的磁场，可以破坏吸积盘。 先前NSF支持的开创性模拟表明，吸积磁化恒星可能处于稳定或不稳定的吸积状态，具有不同的观测特性（有序或随机光变曲线）。 如果圆盘靠近星星，它会通过边界层相互作用，模拟显示出开尔文-亥姆霍兹型不稳定性。 虽然这些模拟和相关的理论分析显示了许多有趣的功能，可以与观测相比，有必要进一步调查磁盘磁层/磁盘星的相互作用，包括某种类型的磁旋转不稳定性（MRI）的可能性。 这个新项目包括专门针对2.5D和3D Godunov型代码的磁盘磁层相互作用的模拟，以模拟相对薄磁盘中MRI驱动的吸积。 相关的理论分析将使我们更深入地了解不同类型的不稳定性在磁盘磁层/磁盘星边界。 由于CTTS在旋转时间尺度上显示出多种变化特征，因此它们的光度和光谱光变曲线将与模拟进行比较。 光谱建模将使用3D蒙特卡罗辐射传输代码。 本研究将探讨磁振造影所驱动的磁化星星吸积现象; 2）从理论和数值上探讨盘-磁层边界和盘-星星边界的不同不稳定性; 3）比较模拟的光变曲线和光谱与不同的CTTS观测结果，结果将适用于不同的磁化恒星，包括CTTS、激变变星、吸积棕矮星和吸积中子星。 这项研究将提供一个有益的例子，将最先进的磁化恒星2.5D和3D模型与最佳观测结果进行比较。 该项目将在多维磁流体力学这一现代领域培训本科生和研究生以及一名博士后研究助理。 结果将包括在讲座本科生，学校的学生，和康奈尔大学的公众游客。 动画可视化最近已经开发出来，并将在各种会谈中使用。 该团队还支持在汤普金斯县科学博物馆的展览。