Above and Below the Substellar Limit at High Resolution

“在高分辨率下的星下极限之上和之下”AST-0098468最近在我们对棕矮星和其他接近星下极限的天体的认识中取得了镜面上的进展。该计划的基础是继续使用凯克望远镜及其各种仪器。根据这一奖项开展的工作将在过去几年中所做的开创性工作的基础上进行和扩大。概述了四个目标。(1)了解低质量天体的双星频率，研究双星的轨道特性。观测将包括光学和红外的梯形光谱，以寻找径向速度。自适应光学将被用来搜索已知的低质量恒星的亚弧秒伴星。(2)测试恒星下质量函数向下延伸到棕矮星和行星之间的边界。这将用低分辨率光谱来完成，主要是为了测试锂的存在。(3)分析光学和近红外中的原子和分子谱线将提供关于非常冷的恒星大气中的物理条件的信息。(4)试图了解在主序的低光度、低质量端的恒星磁活动发生了什么。据推测，正常的恒星活动，类似于我们在太阳上观察到的那样，在这些恒星中大大减少。这些观测将得到最先进的恒星大气理论模型的补充，特别关注尘埃不透明和部分元素枯竭。

" Above and Below the Substellar Limit at High Resolution"AST- 0098468Spectacular advances have been made recently in our knowledge of brown dwarfs and other objects near the substellar limit. The foundation of the program is the continued use of the Keck telescopes and their various instruments. Work carried out under this award will build on and expand upon the pioneering work which has been done during the last few years. Four goals are outlined. (1) To understand the binary frequency among low-mass objects and to investigate the orbital characteristics of binary stars. Observations will include echelle spectroscopy in the optical and infrared to look for radial velocities. Adaptive optics will be utilized to search for sub-arcsecond companions of known low-mass stars. (2) To test the extension of the substellar mass function down to the boundary between brown dwarfs and planets. This will be done with low-resolution spectra, principally to test for the presence of lithium. (3) Analysis of atomic and molecular line profiles in the optical and near infrared will yield information about the physical conditions within very cool stellar atmospheres. (4) An effort to understand what happens to the stellar magnetic activity at the low-luminosity, low-mass end of the main sequence. It is suspected that normal stellar activity, similar to that which we observe in the sun, is greatly diminished in these stars. The observations will be supplemented by state-of-the-art theoretical modeling of the stellar atmospheres with special attention to dust opacity and partial element depletions.