Exploring the coldest observed extrasolar atmospheres with JWST

该项目将重点利用布鲁斯特来了解JWST将在周期1中观测到的极冷Y矮星的大气条件。Y矮星的温度范围从250K到500K左右，代表了太阳系以外直接观测到的最冷的大气层。它们的质量与行星体系重叠，并且人口可能包括被抛出的行星的例子。预计最冷的例子将在其光谱中显示水云的证据，而较热的例子可能显示由卤化物或碱硫化物形成的奇异云。由于温度较低，Y矮星在近红外波段非常微弱，在可见光波段基本上是不可见的。自2011年发现以来，只能通过哈勃望远镜获得质量相对较差的近红外光谱。JWST将提供第一个高质量的光谱，跨越它们发出的大部分光的波长，这将彻底改变我们对这些物体的理解。通过使用布鲁斯特分析这些天体的JWST光谱，该项目将提供对它们的云、化学和热结构的见解。

This project will focus on using Brewster to understand the conditions in the atmospheres of extremely cool Y dwarfs that will be observed by JWST in Cycle 1. Y dwarfs span the temperature range from 250K up to around 500K, and represent the coldest directly observed atmospheres beyond the solar system. Their masses overlap with the planetary regime, and the population may include examples of ejected planets. The coldest examples are expected to show evidence of water clouds in their spectra, whist warmer examples may show exotic clouds formed from halides or alkali sulphides. Due to their cool temperatures, Y dwarfs are extremely faint at near-infrared wavelengths, and are essentially invisible at optical wavelengths. Since their discovery in 2011 it has only been possible to obtain relatively poor quality near-infrared spectra using Hubble. JWST will provide the first high quality spectroscopy across the wavelengths where they emit most of their light, which will revolutionise our understanding of these objects. By using Brewster to analyse JWST spectroscopy of these objects this project will provide the insights to their clouds, chemistry and thermal structure.