A Systematic Data Driven Characterization of the Atmospheres of Brown Dwarfs: At the Boundary Between Stars and Planets

褐矮星大气的系统数据驱动特征：恒星和行星之间的边界

• 批准号: 1615220
• 负责人: Michael Line
• 金额: $ 44.32万
• 依托单位: Arizona State University
• 依托单位国家: 美国
• 项目类别: Standard Grant
• 财政年份: 2016
• 资助国家: 美国
• 起止时间: 2016-08-01 至 2020-12-31
• 项目状态: 已结题
• 来源: https://www.nsf.gov/awardsearch/showAward?AWD_ID=1615220&HistoricalAwards=false
• 关键词: Systematic; Data; Driven; Characterization; Atmospheres

Brown dwarfs are unusual objects in the galaxy. They straddle the boundary between stars and planets - too large to be called planets and too small to be stars. They are not massive enough to fuse hydrogen like stars. Also, their chemical composition often resembles giant gas planets like Jupiter. Studying them presents a great opportunity to learn about atmospheric physics in both stars and planets. This award funds work to study thousands of brown dwarfs using data from public archives. The researchers will update their atmospheric models, and test them with comparisons with their data. Their main database will be the SpeX Prism Spectral Library obtained with the NASA Infrared Telescope Facility. They will also draw conclusions about atmospheric physics based on a detailed statistical study of these brown dwarfs. The results will also be useful to interpreting observations of extrasolar planets. A graduate student and several undergraduate students will participate in the research, including minorities. The PI will work with the Society for Advancement of Chicanos/Hispanics and Native Americans in Science (SACNAS) to increase the numbers of Hispanics and Native Americans in science. The team will apply Bayesian atmospheric retrieval techniques, widely employed in the extrasolar planet community, to a large sample of brown dwarfs. These tools will be used to determine cloud properties and thermal structures and chemistries across a broad range of temperatures and gravities. In particular, they will address outstanding brown dwarf issues such as the behavior of clouds across the low mass L-T transition, the evolution of disequilibrium chemistry with temperature, and the first measure of the distribution of metallicities and carbon-to-oxygen ratios with the populations. First, they will upgrade their models to include high-temperature opacities and different thermal profiles. Next, they will apply their analysis across the entire SpeX database and explore the relationships between temperature, cloud properties, and molecular abundances and publish results. Ultimately, they will finish retrieval analysis on all SpeX objects and apply to other available datasets for brown dwarfs.

棕色矮人是银河系中不寻常的物体。它们跨越了恒星和行星之间的边界 - 太大而被称为行星，太小而无法成为恒星。它们不够大，无法像恒星那样融合氢。而且，它们的化学成分通常类似于木星等巨型气体行星。研究它们为学习恒星和行星的大气物理学提供了一个很好的机会。该奖项为使用公共档案馆的数据研究数千个棕色矮人提供了努力。研究人员将更新其大气模型，并通过与数据进行比较测试。他们的主要数据库将是使用NASA红外望远镜设施获得的SPEX PRISM光谱库。他们还将基于对这些棕色矮人的详细统计研究得出有关大气物理学的结论。结果也将有助于解释观测到极性行星的观察。一名研究生和几名本科生将参加包括少数群体在内的研究。 PI将与奇卡诺斯/西班牙裔美国人和美国原住民（SACNAS）的进步协会合作，以增加西班牙裔美国人和美国原住民的数量。该团队将将广泛使用的贝叶斯大气检索技术应用于大量的棕色矮人样本中。这些工具将用于确定广泛温度和重力范围内的云特性，热结构和化学。特别是，它们将解决鲜艳的棕色矮人问题，例如跨质量L-T转变的云行为，不平衡化学与温度的不平衡演变以及金属性和碳与氧气比与人群的首次衡量。首先，他们将升级其模型，包括高温不良和不同的热轮廓。接下来，他们将在整个SPEX数据库中应用分析，并探索温度，云特性和分子丰度之间的关系并发布结果。最终，他们将完成对所有SPEX对象的检索分析，并将其应用于其他可用的棕色矮人数据集。