Understanding Substellar Atmospheres: Constraining Physical Properties and Testing Models for Brown Dwarfs and Exoplanets

这些凉爽的褐矮星天体跨越了温度较高的恒星和温度较低的气态巨行星之间的间隙。科学家研究这些褐矮星天体，以了解行星和恒星是如何形成的。 T 型矮星是褐矮星的一个子集，是这些天体中温度最低、分布最密集的一组。因此，它们可以很好地模拟大型系外行星的凉爽大气层。然而，我们不了解它们的大气特性。研究人员将研究那些较冷的亚恒星天体，包括 T 矮星和具有行星质量的伴星，以及介于两者之间的过渡天体。他们将了解这些天体的大气、重力、尘埃和云的特性，并利用这些信息开发模型来描述这些星际天体的特性。这项研究通过增加我们对这些行星和恒星之间过渡物体的了解来服务于国家利益，有助于我们对行星形成的理解。纽约市立大学学院的本科生将从事这项研究。像 Astronomy on Tap 计划和海登天文馆演示这样不同的公共外展活动将吸引不同的公众受众。 褐矮星天体（其中 T 矮星是最冷的、分布最广的光谱类别）是系外行星凉爽大气层的有前途的类似物，但其大气层特性的多样性尚未得到很好的了解。主要研究人员和团队将对冷的亚恒星天体进行全面研究，包括 L-T 过渡天体、T 矮星、Y 矮星和行星质量伴星。该团队将得出物理和大气特性；识别和校准次要参数的光谱诊断，例如这些星下物体的重力、金属丰度和尘埃/云特性；并提供模型拟合的详细反馈；从而为系外行星大气研究奠定了基础。该团队拥有数据和分析工具来管理基准对象、生成模板光谱并识别光谱异常值；创建光谱能量分布；计算辐射光度；将大气模型的合成光谱拟合为低、中、高分辨率光谱；使用运动学和进化模型约束年龄、半径和质量；并策划基准和异常对象的公开汇编。主要研究人员是棕矮星光谱实证分析、棕矮星光度和运动学分析以及冷模型大气合成光谱分析方面的专家。来自纽约市立大学学院学生群体的本科生将被纳入与这项研究相关的项目。 Astronomy on Tap 计划、STARtorial 科学时尚博客、Hayden 天文馆演示和 AstroBetter 网站等公共宣传活动将接触到不同的公众受众并与之互动。

The cool brown dwarf objects span the gap between stars with hotter temperatures and gas giant planets with much cooler temperatures. Scientists study these brown dwarf objects to understand how both planets and stars formed. The T dwarfs, a subset of the brown dwarfs, are the coolest well-populated group of these objects. Thus, they could be good analogs for the cool atmospheres of large exoplanets. However, we do not understand their atmospheric properties. The investigators will study those cooler substellar objects including T dwarfs and companions having planetary masses, and in-between transition objects. They will learn about the atmospheres, gravity, dust and cloud properties of these objects, and use this information to develop models to describe the properties of these substellar objects. This research serves the national interest by increasing our knowledge of these objects that are transitional between planets and stars, contributing to our understanding of planet formation. Undergraduate students from the CUNY colleges will work on this research. Public outreach events as different as the Astronomy on Tap program and Hayden Planetarium presentations will reach a diverse public audience.Brown dwarf objects, of which T dwarfs are the coolest well-populated spectral class, are promising analogs for the cool atmospheres of exoplanets, but the diversity of their atmospheric properties is not yet well understood. The principal investigators and team will conduct a comprehensive study of cool, substellar objects, including L-T transition objects, T dwarfs, Y dwarfs, and planetary-mass companions. The team will derive the physical and atmospheric properties; identify and calibrate spectral diagnostics of secondary parameters like gravity, metallicity, and dust/cloud properties of these substellar objects; and provide detailed feedback from model fits; thus establishing a foundation for exoplanet atmosphere studies. The team has the data and analysis tools in hand to curate benchmark objects, generate template spectra, and identify spectral outliers; create spectral energy distributions; calculate bolometric luminosities; fit synthetic spectra from atmospheric models to low, medium, and high resolution spectra; constrain age, radius, and mass using kinematics and evolutionary models; and curate a public compilation of benchmark and outlier objects. The principal investigators are experts in empirical analysis of brown dwarf spectra, photometric and kinematic analysis of brown dwarfs, and analysis with synthetic spectra from cool model atmospheres. Undergraduate students from the student population of the CUNY colleges will be incorporated in projects related to this research. Public outreach events such as the Astronomy on Tap program, STARtorial science fashion blog, Hayden Planetarium presentations, and the AstroBetter website, will reach and interact with a diverse public audience.