Properties of Low Mass Stars and Brown Dwarfs: Single vs. Close Binary Environments

AST 0205875PI Hawley Sloan Digital Sky Survey(SDSS)已经证明，它是寻找低质量恒星、棕矮星和激变变星等近双星的无与伦比的资源。该项目将在未来3年内使用SDSS的光度和光谱数据，以积累一个关于低质量恒星的大型数据库，包括单星和近双星。将获得更多后续数据。本科生和研究生将参与对数据的观察和分析。将为科学家、公众和外联活动提供一个在线数据库。对晚型恒星的星等、颜色、光谱类型、磁活动水平、自转速度和年龄的测量将被用来推断基本的物理性质(温度、光度、质量和磁发电机的强度)，然后对处于不同演化阶段的物体在单星和近双星环境中进行比较，以评估磁活动对自转速度的依赖，发现和表征具有比先前发现的更低质量次级星的密切相互作用的双星系统，研究辐射对近双星中低质量次级星的影响，以确定这是否强烈影响激变变星的爆发，确定低质量单星的空间密度和光度函数，并将其与双星系统中的对应恒星进行比较。***

AST 0205875PI HawleySloan Digital Sky Survey (SDSS) has demonstrated that it is an unsurpassed resource for finding low mass stars, brown dwarfs and close binaries such as cataclysmic variables. This project will use the ongoing SDSS photometric and spectroscopic data during the next 3 years to amass a large database on low mass stars, both single and in close binaries. Additional follow-up data will be obtained. Undergraduate and graduate students will participate in the observations and analysis of the data. An on-line database will be made available for scientists, the public, and outreach activities. Measurements of the magnitudes, colors, spectral types, magnetic activity levels, rotation rates and ages of the late type stars will be used to infer basic physical properties (temperature, luminosity, mass and strength of the magnetic dynamo), which then will be compared for objects at different evolutionary stages in both single and close binary environments to assess the dependence of magnetic activity on rotation rate, to discover and characterize close interacting binary systems with lower mass secondaries than have previously been found, study the influence of irradiation on the low mass secondaries in close binaries, to determine if this strongly affects the outbursts in cataclysmic variables, and to determine the space density and luminosity function of low mass single stars compared with their counterparts in binary systems. ***