Opacity of H- at High Density

白矮星是质量与太阳相似的恒星演化的最终产物。具有氢大气的老白矮星具有高密度和低温的光球。决定其光谱外观的不透明度的主要来源是负氢离子，氢分子的碰撞诱导吸收以及氢原子和分子的瑞利散射。在这些白矮星颜色的理论预测中，最大的不确定性来源是高密度负氢离子的不透明性。对于密度大于0.001克/立方厘米的物质，这种不透明度以前没有被精确计算过，在这种状态下，邻近的粒子会扰乱离子的束缚态结构。这个项目是研究碰撞如何改变负氢束缚态的性质，包括它的结合能，它的配分函数，它的热力学丰度，它的无束缚和自由-自由横截面。项目主管将计算高密度离子的不透明度。更广泛的影响。该研究项目将教育和培训个人如何应用基础物理学来解决复杂问题。参与者包括刚开始从事科学事业的学生，以及将把自己的技能扩展到新领域的经验更丰富的个人。培训将有助于培养一批精通科学的、对技术先进的社会具有普遍效用的个人。在K-12年级的拓展项目中，项目主任将与两个科学博物馆（科学中心和地球博物馆）合作，就我们对太阳和其他恒星的基本可观测特征（大小、亮度、颜色）的现代科学理解进行互动讨论。将在相关的基本微物理过程（核、原子和分子，包括那些研究项目的主题）和太阳的可观测特性之间建立直接联系。

White dwarfs are the end product of stellar evolution for stars of mass similar to the Sun. Old white dwarfs with hydrogen atmospheres have photospheres with high densities and low temperatures. The dominant sources of opacity determining their spectral appearance are the negative hydrogen ion, collision induced absorption of the hydrogen molecule, and Rayleigh scattering of hydrogen atoms and molecules. The greatest source of uncertainty in the theoretical prediction of the colors of these white dwarfs is the opacity of the negative hydrogen ion at high density. This opacity has not previously been calculated accurately for matter densities greater then 0.001 grams per cubic centimeter, a regime in which neighboring particles perturb the ion's bound state structure. This project is a study of how collisions modify the properties of the negative hydrogen bound state, including its binding energy, its partition function, its thermodynamic abundance, and its bound-free and free-free cross sections. The project director will calculate the opacity of this ion at high densities.Broader Impact. The research program will educate and train individuals in the application of basic physics to complex problems. The participants include students just starting a career in science, as well as individuals with more experience who will extend their skills to new areas. The training will contribute to the development of a proficient, scientifically informed group of individuals of general utility to a technologically advanced society. In an outreach program for levels K-12, the project director will partner with two science museums (the Science Center and the Museum of the Earth) and present interactive discussions on the topic of our modern scientific understanding of the basic observable features (size, brightness, color) of the Sun and other stars. A direct connection will be made between relevant fundamental microphysical processes (nuclear, atomic and molecular, including those that are the subject of the research program) and the observable properties of the Sun.