Above and Below the Substellar Limit at High Resolution

高分辨率下的亚恒星极限之上和之下

• 批准号: 0098468
• 负责人: Gibor Basri
• 金额: $ 27.6万
• 依托单位: University of California-Berkeley
• 依托单位国家: 美国
• 项目类别: Continuing Grant
• 财政年份: 2001
• 资助国家: 美国
• 起止时间: 2001-07-01 至 2006-06-30
• 项目状态: 已结题
• 来源: https://www.nsf.gov/awardsearch/showAward?AWD_ID=0098468&HistoricalAwards=false
• 关键词: Above; Below; Substellar; Limit; Resolution

" 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.

AST-0098468最近，我们对褐矮星和其他接近亚恒星极限的天体的了解取得了惊人的进展。该计划的基础是继续使用凯克望远镜及其各种仪器。在该奖项下开展的工作将建立在过去几年所做的开创性工作的基础上并加以扩大。提出了四个目标。(1)了解低质量物体中的双星频率，并研究双星的轨道特征。观测将包括光学和红外线中阶梯光谱学，以寻找径向速度。自适应光学将用于搜索已知低质量恒星的亚弧秒伴星。(2)为了测试亚恒星质量函数的延伸到棕矮星和行星之间的边界。这将通过低分辨率光谱来完成，主要是为了测试锂的存在。(3)光学和近红外线的原子和分子谱线分析将产生关于非常冷的恒星大气中的物理条件的信息。(4)试图了解在主序星低光度、低质量端的恒星磁活动发生了什么。人们怀疑，在这些恒星中，正常的恒星活动，类似于我们在太阳中观察到的活动，大大减少了。观测将得到恒星大气层最先进的理论建模的补充，特别关注尘埃不透明度和部分元素耗尽。