Theoretical and Observational Studies of the Nova Outburst

新星发生在灾难性的双星系统中，在这个双星系统中，一颗充满罗氏叶的次级星正通过内部拉格朗日点向一颗白矮星主星流失富氢物质。白矮星上积累的物质外壳对热核失控是不稳定的，对这一现象的流体动力学模拟再现了许多观测到的新星爆发的特征。提出的研究分为两个主要领域：经典新星爆发的理论研究和相关主题，使用PI的流体动力学-核合成恒星演化代码加上新的辐射-流体动力学代码，此外，光学观测研究支持理论研究。理论上需要回答的问题是：(1)由于几乎所有经过充分研究的新星在爆炸喷出的物质中都表现出富集的核丰度，那么这种富集的来源是什么？(2)由于许多新星的喷出物富含氧、氖和镁，那么ONeMg白矮星吸积的结果是什么？为什么这些新星会喷射出如此多的物质？(3)既然V1500 Cygni和GQMus都被确定为包含磁化白矮星（AM Her变量）的双星系统，那么强磁场对爆发的影响是什么？(4)由于ROSAT和IUE卫星对新星的观测现在已经测量了V1974 Cygni和GQMus的关闭时间，是什么原因导致白矮星停止核燃烧并恢复平静？(5)既然我们现在有了大量关于新星爆发的数据，如V1974 Cyg、cas1993和LMC 1990#1，那么我们能在多大程度上模拟这些新星的爆发呢？(6)既然所有快速新星似乎都经历了一个超爱丁顿光度的阶段，那么产生这个阶段的关键因素是什么？最后，将继续进行光学观测，以研究爆发中新星的演化，并确定能量b预算，元素丰度和关闭时间。＊＊＊

Starrfield 9417057 Novae occur in cataclysmic binary systems in which a Roche lobe filling secondary is losing hydrogen-rich material through the inner Lagrangian point onto a white dwarf primary. The accumulating shell of material on the white dwarf is unstable to a thermonuclear runaway and hydrodynamic simulations of this phenomenon reproduce many of the observed features of the nova outburst. The proposed research falls into two main areas: theoretical studies of the classical nova outburst and related topics using both the PI s hydrodynamic-nucleosynthesis stellar evolution code plus a new radiation-hydrodynamic code and, in addition, optical observational studies in support of the theoretical investigations. The questions to be answered theoretically are: (1) Since virtually all well studied novae exhibit enriched nuclear abundances in the material ejected by the explosion, what is the source of that enrichment? (2) Since many recent novae exhibit ejecta enriched in oxygen, neon, and magnesium, what are the consequences of accretion onto ONeMg white dwarfs and why do these novae eject so much material? (3) Since both V1500 Cygni and GQMus have been identified as binary systems containing magnetized white dwarfs (AM Her variable), what are the consequences of strong magnetic fields on the outburst? (4) Since observations of novae by the ROSAT and IUE satellites have now measured the turn off times for V1974 Cygni and GQMus, what is the cause of the cessation of nuclear burning and the return to quiescence of the white dwarf? (5) Since we now have superb collections of data on the outbursts of a number of recent novae such as V1974 Cyg, Cas 1993, and LMC 1990#1, how well can we simulate the outbursts of these novae? (6) Since all fast novae seem to experience a phase of super-Eddington luminosity, what are the critical factors that produce this phase? Finally, optical observations to study the evolution of novae in outburst and determine energy b udgets, elemental abundances, and turn off times will be continued. ***