Probing planet atmospheres and finding small planets nearby: paving the way for detecting life elsewhere

探测行星大气层并寻找附近的小行星：为探测其他地方的生命铺平道路

• 批准号: RGPIN-2018-05814
• 负责人: Lafrenière, David
• 金额: $ 3.64万
• 依托单位: Université de Montréal
• 依托单位国家: 加拿大
• 项目类别: Discovery Grants Program - Individual
• 财政年份: 2020
• 资助国家: 加拿大
• 起止时间: 2020-01-01 至 2021-12-31
• 项目状态: 已结题
• 来源: https://www.nserc-crsng.gc.ca/ase-oro/Details-Detailles_eng.asp?id=713870
• 关键词: Probing; planet; atmospheres; finding; small

Thousands of exoplanets have been discovered over the past two decades, enabling us to considerably expand our knowledge of their occurrence rate and bulk properties. The findings to date have triggered significant work to improve models of planet formation and evolution, and fuel our quest to find life elsewhere. The exoplanets caught in transit around bright stars allow us to peek through their atmosphere, and already we have detected a few molecules and placed loose constraints on the physical conditions in exoplanet atmospheres. However, the observations within our reach with current facilities face important limitations. Starting operation in late 2019, the James Webb Space Telescope (JWST) will completely revolutionize this field. I am a member of the instrument team of NIRISS, one of the four instruments of JWST, and using 200 hours of our guaranteed JWST observing time, I will lead a program to use NIRISS to acquire transit and eclipse spectroscopy observations of a sample of 16 exoplanets that span the full available range of equilibrium temperatures (300-3000 K) and masses (1 MEarth-10 MJup) for planets amenable to atmospheric characterization. Our observations will measure the abundance of the molecules and aerosols present in the exoplanets' atmosphere and determine their vertical and horizontal temperature structure with unprecedented precision. In turn this will allow us to address fundamental issues such as the formation process of planets and their subsequent evolution, the presence and characteristics of particulate clouds in planets' atmosphere, and non-equilibrium chemistry effects that might be at play in their atmosphere. Four of our targets are rocky and for these we intend to place some of the first constraints on the mean molecular weight and hence bulk composition of their atmosphere. I am also a member of the science teams of SPIRou and NIRPS, two new high-resolution, fiber-fed, near-infrared échelle spectrographs capable of precision radial velocity measurements. I will use these new powerful instruments to probe exoplanet atmospheres using the relatively new technique of high dispersion spectroscopy. These observations will be highly complementary to the lower resolution JWST observations, improving our determination of atmospheric composition and providing new information about the flow of gas in the planets' atmosphere. Using SPIRou and NIRPS, I will also participate in large radial velocity surveys to find new rocky planets around low-mass stars in the immediate neighborhood of the Sun. These surveys will uncover the best earth-like planets to search for biosignatures in the near-future, given their bright hosts and short orbital periods, and will provide a robust determination of the fraction of low-mass stars that host a habitable earth-like planet.

在过去的二十年里，已经发现了数千颗系外行星，使我们能够大大扩展我们对它们的发生率和整体性质的了解。到目前为止，这些发现已经引发了改进行星形成和演化模型的重要工作，并推动了我们在其他地方寻找生命的探索。在明亮恒星周围过境的系外行星使我们能够窥视它们的大气层，我们已经检测到一些分子，并对系外行星大气层的物理条件进行了宽松的限制。然而，在我们现有设施范围内的观测面临着重要的限制。从2019年底开始运行，詹姆斯韦伯太空望远镜（JWST）将彻底改变这一领域。 我是JWST的四个仪器之一NIRISS仪器团队的成员，并使用我们保证的JWST观测时间的200小时，我将领导一个项目，使用NIRISS获取16颗系外行星样本的凌日和日食光谱观测，这些行星跨越了平衡温度的全部可用范围。（300-3000 K）和质量（1 MEarth-10 MJup）的行星适合大气特征。我们的观测将测量系外行星大气中存在的分子和气溶胶的丰度，并以前所未有的精度确定它们的垂直和水平温度结构。反过来，这将使我们能够解决一些基本问题，例如行星的形成过程及其随后的演变，行星大气中微粒云的存在和特征，以及可能在其大气中发挥作用的非平衡化学效应。我们的目标中有四个是岩石，对于这些目标，我们打算对平均分子量以及它们大气的整体组成进行一些初步的限制。 我也是SPIRou和NIRPS科学团队的成员，这两个新的高分辨率，光纤馈电，近红外échelle光谱仪能够精确测量径向速度。我将使用这些新的强大的仪器来探测系外行星的大气层，使用相对较新的高色散光谱技术。这些观测结果将与较低分辨率的JWST观测结果高度互补，改善我们对大气成分的测定，并提供有关行星大气中气体流动的新信息。使用SPIRou和NIRPS，我还将参与大型径向速度调查，以发现太阳附近低质量恒星周围的新岩石行星。这些调查将发现最好的类地行星，在不久的将来寻找生物特征，考虑到它们明亮的宿主和短的轨道周期，并将提供一个可靠的确定低质量恒星的比例，宿主一个可居住的类地行星。