Signatures of Shocks and Particle Acceleration from Novae in our Galaxy

1. 新星爆发是由白矮星表面氢失控的热核燃烧引起的能量输出的急剧增加。通常情况下，一颗白矮星（一颗质量与太阳相当的恒星，体积与地球相当）几乎不含氢。然而，如果它有一颗普通的恒星作为伴星，白矮星有时会从伴星那里积累氢到它的表面。只要太阳质量的万分之几就足以引发这种氢燃料的热核“燃烧”。失控的氢燃烧产生了观测到的新星爆发，并从白矮星猛烈地喷射出质量。最近的宇宙飞船观测揭示了新星爆发时的伽马射线辐射。这些观察结果表明，流体动力冲击发生在新星中。本研究旨在利用计算机模拟来研究这些冲击的起源、外观和影响。这项工作将大大提高对新星爆发期间许多不同波长辐射的理解。它也会提高科学家的能力。对离子和电子加速到极高能量的理解。这项工作的智力价值来自于这些进步。本科生参与研究、透过电影及互动网站向公众宣传，是本研究较好的广泛影响。新星是由白矮星表面失控的热核燃烧提供能量的突然爆发，白矮星从伴星中吸积了物质。最近在新星爆发期间发现的GeV伽马射线提供了一个惊人的迹象，表明这些系统中发生了流体动力冲击。该项目将采用流体力学计算来研究新星中冲击的起源、外观和影响。这项工作还将研究电子和离子的激波加速效率以及激波时的磁场放大。此外，将采用数值模拟和多波长建模相结合的方法来约束各种激波参数。这项研究的智力价值来自于对新星发射和天体物理学中粒子加速机制的进一步理解。结果也将为瞬态现象的无线电和光学调查提供信息。这项工作的广泛影响不仅包括为本科生提供研究机会，还包括通过互动网站、彩色电影和为高中教师举办的研讨会进行公众宣传。

1. A nova eruption is a dramatic increase in energy output caused by runaway thermonuclear burning of hydrogen on the surface of a white dwarf star. Ordinarily, a white dwarf (a star with the mass of our Sun crammed into a volume about the size of the Earth) contains little or no hydrogen. If it has an ordinary star as a companion, however, a white dwarf can sometimes accumulate hydrogen from the companion onto its surface. As little as a few ten-thousandths of the mass of our Sun can be enough to trigger the thermonuclear "burning" of this hydrogen fuel. Runaway hydrogen burning produces the observed nova outburst and violently ejects mass from the white dwarf. Recent spacecraft observations have revealed gamma-ray emission during nova outbursts. These observations demonstrate that hydrodynamic shocks occur in novae. This research aims to use computer simulations to study the origin, appearance, and implications of these shocks. The work will greatly improve the understanding of emission at many different wavelengths during nova outbursts. It will also improve scientists? understanding of the acceleration of ions and electrons to extremely high energies. The Intellectual Merit of the work comes from such advances. The involvement of undergraduate students in the research and public outreach through movies and an interactive website are good Broader Impacts of the research.2. Novae are sudden outbursts of energy powered by runaway thermonuclear burning on the surface of a white dwarf that has accreted matter from a stellar companion. The recent discovery of GeV gamma rays emitted during nova outbursts provides a striking indicator that hydrodynamic shocks occur in these systems. This project will employ hydrodynamic calculations to study the origin, appearance, and implications of shocks in novae. The work will also investigate the efficiency of shock acceleration of electrons and ions as well as magnetic-field amplification at the shock. In addition, the combination of numerical simulations and multi-wavelength modelling will be used to constrain various shock parameters. The Intellectual Merit of the research derives from improved understanding of emission from novae and of a mechanism of particle acceleration in astrophysics. The results will also inform both radio and optical surveys for transient phenomena. The Broader Impacts of the work will involve not only research opportunities for undergraduates but also public outreach through an interactive website, color movies, and a workshop for high school teachers.