Exploring the coldest observed extrasolar atmospheres with JWST

该项目将侧重于使用布鲁斯特来了解JWST将在第一周期观测的极冷Y矮星的大气条件。Y矮星的温度范围从250 K到500 K左右，是太阳系外直接观测到的最冷的大气。它们的质量与行星体系重叠，并且人口可能包括弹射行星的例子。最冷的例子预计会在其光谱中显示水云的证据，而较温暖的例子可能会显示由卤化物或碱硫化物形成的奇异云。由于它们的低温，Y矮星在近红外波长处非常微弱，在光学波长处基本上不可见。自2011年发现以来，只能使用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学，跨越它们发出大部分光的波长，这将彻底改变我们对这些物体的理解。通过使用布鲁斯特来分析这些物体的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.