Circumstellar Matter: Neutral Envelopes and Planetary Nebula Formation

AST0307277PI Huggins这是一个研究恒星在红巨星膨胀阶段过渡到最终缩小的白矮星形式时抛出的物质的项目，这是恒星演化的关键阶段，终止了所有低质量和中等质量恒星的正常生命。恒星抛出的物质形成了一个由中性气体和尘埃组成的不断膨胀的星际包层，形成了行星状星云。观测被用来解决这一演化序列的关键方面，例如恒星在生命末期失去质量的方式，以帮助确定控制质量损失过程的机制，行星星云的复杂对称性如何被高速双极喷流印在它们的中性星云包层上，以及演化的行星星云中性包层如何分裂成大量彗星球体。在这项工作的过程中，正在测试基本的气体动力学模型。更广泛的影响：拟议工作的更广泛影响具有强烈的教育重点。这些措施包括对学生进行研究方面的直接培训和主要调查员的协同专业发展，其中包括对学生的指导，促进对K-12科学教师的培训，以及为天文学教学开发新的设施和课程材料。该计划还促进了国际合作，其结果将在学科内外广泛传播。

AST 0307277PI HugginsThis is a project studying the matter ejected during the red giant expansion phase of stars as they transition into their final shrunken white dwarf forms, the crucial stage of stellar evolution that terminates the normal lives of all low and intermediate mass stars. The mass ejected by the stars forms an expanding circumstellar envelope of neutral gas and dust that develops into a planetary nebula. Observations are being used to address key aspects of this evolutionary sequence, such as the ways in which stars lose mass toward these end stages of their lives, to help identify the mechanisms governing the mass-loss process, how the complex symmetries of planetary nebulae are imprinted on their neutral circumstellar envelopes by high velocity bipolar jets, and how the neutral envelopes of evolved planetary nebulae fragment into arrays of numerous cometary globules. Basic gas dynamical models are being tested in the course of this work.Broader impacts: The broader impacts of the proposed work have a strong educational focus. They include the direct training of students in research and the synergistic professional development of the principle investigator which includes the mentoring of students, contributing to the training of K-12 science teachers, and the development of new facilities and curricular materials for the teaching of astronomy. This program also fosters international cooperation, and the results will be widely disseminated within and beyond the discipline.