Infrared Studies of Transient Events: Classical Novae and Variable Stars

Gehrz，Robert 95-28336经典新星和发光演化(主序后)恒星是在恒星演化过程中被循环到星际介质周围的加工物质的重要来源。关于这些流出的尘埃和气体的定量信息对于为银河系化学演化模型提供基本约束是必要的。红外(IR)光度和光谱分析是评估星周物质固相和气相丰度的特别强大的工具。红外分光光度法、成像法和旋光法可以用来推断星周流出的物理特征和在其中形成的颗粒的物理特征。明尼苏达大学IR小组计划延长三年，通过对经典新星爆炸的时间发展和发光IR变星的瞬时活动的红外观测来研究恒星周围的尘埃和气体。这些研究将表征星周流出的天体物理尘埃颗粒的成核和生长，评估新星和红外变星对ISM的固体和气相物质的贡献，并提供关于质量损失过程之前的恒星演化阶段的信息。要成功实现许多计划目标，需要及时观测到多个波长的突然、瞬时活动。这项研究将建立在以前观测的基础上，并将受益于它们利用明尼苏达州、怀俄明州和亚利桑那州的望远镜对瞬变事件进行及时、远程和同时的多波长观测的能力。***

Gehrz, Robert 95-28336 Classical novae and luminous evolved (post main sequence) stars are important sources of processed material that is recycled to the interstellar medium (ISM) in circumstellar outflows during stellar evolution. Quantitative information about the dust and gas ejected in these outflows is necessary to provide fundamental constraints on models of Galactic chemical evolution. Infrared (IR) photometry and spectroscopy are particularly powerful tools for evaluating the abundances of both solid and gaseous phases of circumstellar material. IR spectrophotometry, imaging and polarimetry can be used to deduce the physical characteristics of the circumstellar outflows and of the grains that form within them. A three year extension is planned to the University of Minnesota IR group's program to study circumstellar dust and gas through IR observations of the temporal development of classical nova explosions and the transient activity of luminous IR variable stars. The studies will characterize the nucleation and growth of astrophysical dust grains in circumstellar outflows, asses the contributions of solid and gas-phase matter that novae and IR variable stars make to the ISM, and provide information about the stages of stellar evolution that preceded the mass loss process. Successful fulfillment of many of the program objectives requires prompt observations of sudden, transient activity at many wavelengths. The study will build upon previous observations and will benefit from their capabilities to obtain timely, remote and simultaneous multi-wavelength observations of transient events with telescopes in Minnesota, Wyoming and Arizona. ***