Extreme mass ratio multiple stellar systems: understanding the origin of the brown dwarf desert and directly imaged planets

该奖项资助了一个观测项目，以确定大质量恒星(质量是太阳的3-8倍)的近距离、极低质量恒星伴星的频率。这些结果将被用来测试恒星形成过程的物理极限，并更好地理解所谓的“棕矮星沙漠”现象的存在，这一现象被用来描述在大约3-5个天文单位(AU)的双星范围内的褐矮星的稀缺性，并在行星和恒星形成模型中发挥着重要作用。天文单位是一个长度单位，大约等于地球和太阳之间的距离。结果将被用来测试恒星形成模型和在棕矮星和系外行星搜索中发现的亚恒星同伴的性质。它们还将为太阳系外行星(围绕其他恒星运行的行星)的成像探测提供有用的背景。PI将监督和指导两名在这个项目上进行研究实习的本科生。为了完成这项工作，研究人员将使用Lick天文台的Shaneao仪器和双子星成像仪的极端自适应光学系统来测量极端质量比双星系统的数量。该项目将包括两种类型的目标：一种来自1kpc以内、小于100 Myr的富年轻星团，另一种来自与星团无关的场星。在数据约简后，从大质量恒星的图像中去掉点扩散函数后，就可以从数据中识别出微弱的伴星。

This award funds an observational program to determine the frequency of close, very low-mass stellar companions to massive stars (those with 3-8 times the mass of the Sun). The results will be used to test the physical limit of the star formation process and to better understand the existence of the so-called "brown dwarf desert" phenomenon, which is used to describe the scarcity of brown dwarfs within about 3-5 astronomical units (AU) of binary stars, and plays a large role in planetary and star formation models. The AU is a unit of length approximately equal to the distance between the Earth and Sun. The results will be used to test star formation models and the nature of sub-stellar companions discovered in brown dwarf and exoplanet searches. They will also provide useful context for extrasolar planet (planets that orbit other stars) imaging surveys. The PI will supervise and mentor two undergraduate students with research internships on this project.To accomplish this work, the researchers will use extreme adaptive optics systems with the ShaneAO instrument at the Lick Observatory and the Gemini Planet Imager in order to measure the number of extreme mass-ratio binary star systems. The project will comprise two types of targets: one from rich young star clusters within 1 kpc and less than 100 Myr, and another from field stars unassociated with clusters. After the data are reduced, faint companions will be identified from the data after point-spread-functions have been removed from the images of the high-mass stars.