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

低温褐矮星横跨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是为了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、人口最多的一组。因此，它们可以很好地模拟大型系外行星的低温大气。然而，我们不了解它们的大气特性。研究人员将研究那些温度较低的亚恒星物体，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物体。他们将了解这些物体的大气、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次恒星物体的特性。这项研究增加了我们对行星和恒星之间过渡天体的认识，有助于我们对行星形成的理解，从而为国家利益服务。来自纽约市立大学各学院的本科生将参与这项研究。像天文直播节目和海登天文馆演讲这样不同的公共宣传活动将吸引不同的公众观众。褐矮星（其中T型矮星是最冷的、人口最多的光谱类）很有希望与系外行星的低温大气类似，但它们的大气特性的多样性还没有得到很好的理解。主要研究人员和团队将对低温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。该团队将得出其物理和大气特性；识别和校准次要参数的光谱诊断，如重力、金属丰度和这些次恒星物体的尘埃/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，可以管理基准对象，生成模板光谱，并识别光谱异常值；创建光谱能量分布；计算热光度；将大气模式合成光谱与低、中、高分辨率光谱拟合；使用运动学和进化模型约束年龄、半径和质量；并策划一个基准和异常对象的公共汇编。主要研究人员是褐矮星光谱的经验分析、褐矮星的光度和运动学分析以及低温模式大气合成光谱分析方面的专家。来自纽约市立大学学生群体的本科生将被纳入与本研究相关的项目。公众宣传活动，如天文直播节目、星际科学时尚博客、海登天文馆演讲和AstroBetter网站，将与不同的公众受众进行互动。

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.