Exploring Young Brown Dwarfs

AST-0205130 PI Jayawardhana在过去的五年里，在太阳附近和恒星形成区发现了大量的亚恒星物体。事实上，褐矮星似乎和恒星一样常见。然而，对它们的起源和早期演化几乎没有观测限制。对年轻棕矮星的研究为它们的形成机制提供了有价值的线索。该计划探索恒星形成区域中褐矮星的物理特性，并将其与研究得更好的主序前恒星进行比较，以揭示它们的起源。该计划采用了许多在金牛座T星研究中开发的方法，包括（1）寻找年轻亚恒星物体周围盘的热红外发射，（2）光学光谱学，以获得它们的吸积光度和质量吸积率，（3）散射光和盘的热发射建模，（4）X射线发射的观测，作为活动的指示器，以及（5）基于光学中的光度变化的旋转周期的测量。 该计划的结果将有助于区分褐矮星的不同形成场景，例如云碎片，原恒星盘不稳定性和新生多系统的喷射，年轻的亚恒星物体是否经历T Tauri阶段。

AST-0205130PI JayawardhanaThe past five years have seen the identification of a large number of sub-stellar objects in the solar neighborhood and in star-forming regions. Indeed, it appears that brown dwarfs maybe as common as stars. However, there are few observational constraints on their origin and early evolution. Studies of young brown dwarfs provide valuable clues to their formationmechanism(s). This program explores the physical properties of brown dwarfs in star-forming regions and compare them to the much better studied pre-main sequence stars, in order to shed light on their origin. The program employs many of the methods developed in the study of T Tauri stars, and includes (1) a search for thermal infrared emission from disks around young sub-stellar objects, (2) optical spectroscopy to derive their accretion luminosities and mass accretion rates, (3) modeling of scattered light and thermal emission of disks, (4) observations of X-ray emission, as an indicator of activity, and (5) measurements of rotation periods based on photometric variability in the optical. The results of this program will help distinguish among different formation scenarios for brown dwarfs, such as cloud fragmentation, protostellar disk instability, and ejection from newborn multiple systems, whether young sub-stellar objects undergo a T Tauri-like phase.***