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arXiv 2302.04794astro-ph.EP
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热海王星WASP-166 b与ESPRESSO III:蓝移的试探性水信号限制了云的存在

The hot Neptune WASP-166 b with ESPRESSO III: A blue-shifted tentative water signal constrains the presence of clouds

M. Lafarga, M. Brogi, S. Gandhi, H. M. Cegla, J. V. Seidel, L. Doyle, R. Allart, N. Buchschacher, M. Lendl, C. Lovis, D. Sosnowska

摘要:

通过高分辨率光谱学,我们可以研究系外行星的大气层,了解它们的化学成分、温度分布以及云和风的存在,主要是在炎热的巨行星上。最先进的仪器正在将这些研究推向更小的系外行星。特别令人感兴趣的是“海王星沙漠”中的几颗行星,缺乏海王星大小的行星在其宿主周围的近轨道上。在这里,我们评估了一颗这样的行星中是否存在水,这颗膨胀的超级海王星WASP-166 b,它在5.4天的短轨道上绕着一颗F9型恒星运行。尽管它的轨道很近,但WASP-166 b保留了它的大气层,使其成为沙漠中系外行星大气研究的基准目标。我们分析了两个凌日观察到的可见光与ESSEMO。我们通过主成分分析从地球的大地吸收中清除光谱,这对于在系外行星中寻找水至关重要。我们使用互相关的可能性映射,同时估计水的丰度和云层的高度,这指向一个低的水丰度和/或高云的限制。我们试探性地检测到一个水信号蓝移~5 km s-1的行星静止框架。注入和检索模式光谱表明,太阳成分,无云的大气将被检测到在高的意义。由于ESTERO的能力和VLT的收集能力,这只能在可见光中实现。这项工作提供了对海王星沙漠行星WASP-166 b的进一步了解,该行星将与JWST一起观测。

英文摘要:

With high-resolution spectroscopy we can study exoplanet atmospheres and learn about their chemical composition, temperature profiles, and presence of clouds and winds, mainly in hot, giant planets. State-of-the-art instrumentation is pushing these studies towards smaller exoplanets. Of special interest are the few planets in the 'Neptune desert', a lack of Neptune-size planets in close orbits around their hosts. Here, we assess the presence of water in one such planet, the bloated super-Neptune WASP-166 b, which orbits an F9-type star in a short orbit of 5.4 days. Despite its close-in orbit, WASP-166 b preserved its atmosphere, making it a benchmark target for exoplanet atmosphere studies in the desert. We analyse two transits observed in the visible with ESPRESSO. We clean the spectra from the Earth's telluric absorption via principal component analysis, which is crucial to the search for water in exoplanets. We use a cross-correlation-to-likelihood mapping to simultaneously estimate limits on the abundance of water and the altitude of a cloud layer, which points towards a low water abundance and/or high clouds. We tentatively detect a water signal blue-shifted ~5 km s-1 from the planetary rest frame. Injection and retrieval of model spectra show that a solar-composition, cloud-free atmosphere would be detected at high significance. This is only possible in the visible due to the capabilities of ESPRESSO and the collecting power of the VLT. This work provides further insight on the Neptune desert planet WASP-166 b, which will be observed with JWST.

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