Supernova and Supernova Remnant Studies

谢瓦利埃教授和合作者将进行四个项目，这些项目有望大大提高我们对大质量恒星晚期演化的理解，以及它们如何/为什么在超新星中结束生命。其中三个努力的关键是研究超新星喷出物如何与爆炸前恒星脱落的物质相互作用。(1) IIn型超新星，具有相对较窄的发射线，代表超新星与爆炸前不久消失的星团状物质的相互作用，这些物质的质量可达几个太阳。新的无线电和红外发射模型，以及从其他多波长数据推断出来的数据，将与流体动力学模型相结合，以更好地约束质量损失，这显然是偶发的，并将超新星置于大质量恒星演化的背景下。由于这项工作，很可能需要对大质量恒星最终演化的标准观点进行修订。(2) IIP型（平台光曲线）超新星的核心坍缩超新星发生率最高，但奇怪的是，在年轻超新星遗迹中却没有得到很好的代表。假设这是由于一个低密度的周围，正如预期的恒星在祖先质量范围内，将通过流体动力学模拟来评估。这些结果将与包括蟹状星云在内的许多年轻残留物的观测结果进行比较。(3)流体动力学模型，结合粒子演化和非热x射线和射电发射的计算，将用于设定正常Ia型超新星周围质量损失密度的约束条件。预计这些限制将是对祖系统的最大限制。第四个项目将研究大质量恒星核心坍缩后期的非径向不稳定性，这可能是超新星爆炸机制的关键部分。不稳定性的线性分析将用于解决以往研究中的差异，并研究不稳定性的物理机制。这些项目对天体物理学有着广泛的影响，因为它们与大质量恒星的晚期演化、重元素返回星际介质以及高能量密度下的物理过程有关。这项研究还将建立和维持弗吉尼亚大学和斯德哥尔摩天文台之间的联系。研究结果将在会议和座谈会上广泛传播。一名研究生和一名本科生将参与开展这项研究，并将学习理论天体物理学中使用的技术。最后，恒星爆炸的话题是一个吸引公众想象力的话题，研究成果将被整合到本科课程和公开讲座中。

Professor Chevalier and collaborators will undertake four projects that are expected to greatly improve our understanding of the late evolution of massive stars and how/why they end their lives in supernovae. Key to three of these efforts is the study of how supernova ejecta interacts with material shed from stars before the explosion. (1) Type IIn supernovae, with relatively narrow emission lines, represent supernova interaction with up to several solar masses of clumpy circumstellar material that was lost shortly before the explosion. New models for radio and infrared emission, together with inferences from other multiwavelength data, will be combined with hydrodynamic models to better constrain the mass loss, which apparently is episodic, and to place the supernovae in the context of massive star evolution. A revision of the standard view of the final evolution of massive stars may well be required as a result of this work. (2) Type IIP (plateau light curve) supernovae have the highest occurrence rate of core collapse supernovae, but are curiously not well represented among young supernova remnants. The hypothesis that this is due to a low-density surrounding, as expected for stars in the progenitor mass range, will be evaluated through hydrodynamic simulations. The results will be compared to observations of a number of young remnants, including the Crab Nebula. (3) Hydrodynamic models, together with calculations of particle evolution and nonthermal X-ray and radio emission, will be used to set constraints on the mass loss density around normal Type Ia supernovae. The limits are expected to be the strongest for constraining the progenitor system. A fourth project will examine nonradial instability in the late phases of massive star core collapse, which may be a crucial part of the supernova explosion mechanism. A linear analysis of the instability will be used to settle a discrepancy in previous studies and to investigate the physical mechanism for the instability. These projects have broad implications for astrophysics in that they are relevant to the late evolution of massive stars, the return of heavy elements to the interstellar medium, and physical processes at high energy densities. The research will also build and maintain ties between the University of Virginia and Stockholm Observatory. The results will be broadly disseminated at conferences and colloquia. A graduate student and an undergraduate student will be involved in carrying out the research and will learn techniques used in theoretical astrophysics. Finally, the topic of exploding stars is one that captures the public imagination and the research results will be integrated into undergraduate courses and public lectures.