Eclipse Mapping Exoplanet Atmospheres with the James Webb Space Telescope

使用詹姆斯·韦伯太空望远镜绘制系外行星大气日食图

• 批准号: 2814903
• 金额: --
• 依托单位: University of Bristol
• 依托单位国家: 英国
• 项目类别: Studentship
• 财政年份: 2023
• 资助国家: 英国
• 起止时间: 2023 至 无数据
• 项目状态: 未结题
• 来源: https://gtr.ukri.org/projects?ref=studentship-2814903
• 关键词: Eclipse; Mapping; Exoplanet; Atmospheres; James

Our understanding of exoplanets is significantly lacking in comparison to our understanding of the Solar System planets due to the greater difficulties of observing them. Many properties of exoplanets can be uncovered through the study of their atmospheres, which hold key information on their current state and formation history. The most successful exoplanet detection and characterisation method is the transit method, which allows us access to atmospheric information on the nightside hemisphere of an exoplanet whilst they are in transit and on the dayside hemisphere as they are eclipsed by their host star.My research involves using the technique of eclipse mapping to spatially map the atmospheres of transiting exoplanets. If we take snapshot observations as progressive longitudes of the exoplanet enter eclipse, then we can attribute the reductions in system flux to that region of the planet and construct a 1D emission map of the dayside hemisphere of its atmosphere. If the orbit of the planet is inclined from our viewpoint, then higher latitudes will be eclipsed faster than lower latitudes, allowing us to further sub-attribute the flux reductions to different latitudes, extending our map to 2D. Observing the eclipse at multiple wavelengths then even further allows us to measure the emission from multiple depths of the atmosphere, extending the map to 3D.Hot Jupiters (highly irradiated and tidally locked giant exoplanets with day-scale orbital periods) provide the most exemplary conditions for characterising the atmospheres of exoplanets, owing to their often highly inflated atmospheres which promote strong signals. My research focuses on eclipse mapping the dayside hemisphere of the hot Jupiter WASP-17b using Space Telescope GTO programme 1353 (PI: N.K. Lewis) data obtained by the MIRI/LRS and NIRSpec/G395H instruments onboard JWST. WASP-17b is a prime candidate for these types of observations as the day- to night-side temperature range of its atmosphere spans 1000 - 2500 K, making it likely to host a broad range of spectroscopically active chemical species. It is also an interesting target due to its retrograde orbit, which challenges current planet formation theories - my research aims to contribute to bridging gaps such as this in our understanding of planet formation.This work is undertaken as part of the JWST-TST collaboration, with the aim of combining this dataset and others (three transits and three eclipses, one each respectively obtained by the MIRI/LRS, NIRSpec/G395H, and NIRISS/SOSS instrument onboard JWST, covering the 0.6 - 14 micron wavelength range) to produce the first full 3D map of an exoplanet atmosphere, which will allow us to robustly constrain its thermal, compositional, and dynamical properties, contributing momentously to our understanding of all aspects of exoplanet science. Such techniques will then be extended to other types of exoplanets in order to broaden our understanding of their diversity.

与我们对太阳系行星的了解相比，我们对系外行星的了解明显缺乏，因为观察它们更困难。通过对系外行星大气层的研究，可以发现它们的许多特性，大气层掌握着它们当前状态和形成历史的关键信息。最成功的系外行星探测和表征方法是凌日法，它使我们能够获得系外行星在凌日时的夜侧半球和被主星遮挡时的日侧半球的大气信息。我的研究包括使用日食测绘技术对凌日系外行星的大气进行空间测绘。如果我们在系外行星的渐进式经度进入日食时进行快照观测，那么我们可以将系统通量的减少归因于行星的该区域，并构建其大气的日侧半球的1D发射图。如果从我们的角度来看，行星的轨道是倾斜的，那么高纬度地区的日食将比低纬度地区更快，这样我们就可以进一步将通量减少的子属性划分到不同的纬度，将我们的地图扩展到2D。在多个波长观察日食，然后进一步让我们测量大气多个深度的发射，将地图扩展到3D。热木星（具有日尺度轨道周期的高辐射和潮汐锁定的巨大系外行星）提供了表征系外行星大气的最典型条件，因为它们的大气通常高度膨胀，会产生强烈的信号。我的研究重点是利用JWST上的MIRI/LRS和NIRSpec/G395H仪器获得的太空望远镜GTO程序1353 （PI: N.K. Lewis）数据，对热木星WASP-17b的日侧半球进行日食测绘。WASP-17b是这类观测的主要候选者，因为它的大气昼夜温度范围在1000 - 2500 K之间，这使得它很可能拥有广泛的光谱活性化学物质。由于它的逆行轨道，它也是一个有趣的目标，这挑战了当前的行星形成理论-我的研究旨在帮助弥合我们对行星形成的理解中的这种差距。这项工作是JWST- tst合作的一部分，其目的是将该数据集与其他数据集（三次凌日和三次日食，分别由JWST上的MIRI/LRS， NIRSpec/G395H和NIRISS/SOSS仪器分别获得，覆盖0.6 - 14微米波长范围）结合起来，生成第一张系外行星大气的完整3D地图，这将使我们能够有力地约束其热，成分和动力学特性。为我们理解系外行星科学的各个方面做出了重大贡献。这样的技术将扩展到其他类型的系外行星，以扩大我们对它们多样性的理解。