Detection of Na, K, and Hαabsorption in the atmosphere of WASP-52b using ESPRESSO
Detection of Na, K, and Hαabsorption in the atmosphere of WASP-52b using ESPRESSO
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DOI：
10.1051/0004-6361/201936986
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发表时间：
2020-02
影响因子：
6.5
通讯作者：
Guo Chen;N. Casasayas-Barris;E. Pallé;F. Yan;M. Stangret;H. Cegla;R. Allart;C. Lovis
中科院分区：
文献类型：
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作者：
Guo Chen;N. Casasayas-Barris;E. Pallé;F. Yan;M. Stangret;H. Cegla;R. Allart;C. Lovis
WASP-52b 是一颗低密度热木星，围绕一颗中等活跃的 K2V 恒星运行。之前的低分辨率研究揭示了云层的大气层，并在云层上方发现了原子钠。在此，我们报告了 Na 双峰、Hα 线和 K D1 线处过量吸收的检测。我们根据 WASP-52b 的三次凌日得出了高分辨率透射光谱，并使用甚大望远镜阵列中的超稳定、高分辨率摄谱仪 ESPRESSO 进行了观测。我们测得 Na D1 的线对比度为 1.09 ± 0.16%，Na D2 的线对比度为 1.31 ± 0.13%，Hα 的线对比度为 0.86 ± 0.13%，K D1 的线对比度为 0.46 ± 0.13%，线 FWHM 范围为 11–22 km s−1。我们还发现，这些探测到的线在凌日过程中的速度变化与行星的轨道运动一致，从而证实了它们的行星起源。我们没有观察到任何可归因于行星风的显着净蓝移或红移。我们使用活性指示线作为对照，但没有发现过量吸收。然而，我们确实注意到这些控制线上的中心到肢体变异 (CLV) 和罗西特-麦克劳林 (RM) 效应产生的特征。这凸显了 CLV + RM 校正在正确导出透射光谱方面的重要性，如果不进行校正，在某些情况下可能会类似于或抵消行星吸收。 WASP-52b 是继 HD 189733b 之后第二个显示出过量 Hα 吸收的非超热木星。未来针对非超热木星的观测表明，Hα可以帮助揭示恒星活动与行星高层大气加热过程之间的关系。
WASP-52b is a low-density hot Jupiter orbiting a moderately active K2V star. Previous low-resolution studies have revealed a cloudy atmosphere and found atomic Na above the cloud deck. Here we report on the detection of excess absorption at the Na doublet, the Hαline, and the K D1line. We derived a high-resolution transmission spectrum based on three transits of WASP-52b, observed with the ultra-stable, high-resolution spectrograph ESPRESSO at the Very Large Telescope array. We measured a line contrast of 1.09 ± 0.16% for Na D1, 1.31 ± 0.13% for Na D2, 0.86 ± 0.13% for Hα, and 0.46 ± 0.13% for K D1, with a line FWHM range of 11–22 km s−1. We also found that the velocity shift of these detected lines during the transit is consistent with the planet’s orbital motion, thus confirming their planetary origin. We did not observe any significant net blueshift or redshift that could be attributed to planetary winds. We used activity indicator lines as control but found no excess absorption. However, we did notice signatures arising from the Center-to-Limb variation (CLV) and the Rossiter-McLaughlin (RM) effect at these control lines. This highlights the importance of the CLV + RM correction in correctly deriving the transmission spectrum, which, if not corrected, could resemble or cancel out planetary absorption in certain cases. WASP-52b is the second non-ultra-hot Jupiter to show excess Hαabsorption after HD 189733b. Future observations targeting non-ultra-hot Jupiters that show Hαcould help reveal the relation between stellar activity and the heating processes in the planetary upper atmosphere.