LRG-BEASTS: evidence for clouds in the transmission spectrum of HATS-46 b
LRG-BEASTS: evidence for clouds in the transmission spectrum of HATS-46 b
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LRG-BEASTS：HATS-46 b 透射光谱中存在云的证据
DOI：
10.1093/mnras/stad779
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发表时间：
2023
影响因子：
4.8
通讯作者：
Ahrer E
中科院分区：
文献类型：
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作者：
Ahrer E
我们使用ESO新技术望远镜（NTT）上的EFOSC 2仪器对HATS-46 b B进行了透射低分辨率地基光谱测量。HATS-46 B是一颗高度膨胀的系外行星，是透射光谱学的主要目标，其半径（0.95 RJup）类似于彗星，但质量要小得多（0.16 MJup）。它围绕一颗周期为4.7 d的G型星星运行，平衡温度为1100 K。我们用NTT观测到HATS-46 B的一次凌日，时间序列光谱覆盖波长范围为3900-9000 nm，分辨率（R）为380 nm。我们获得了非常精确的1.03倍光子噪声的透射光谱，对于200个宽的仓，中值不确定度为357 ppm，尽管宿主星星相对较暗，Vmag = 13.6。透射光谱没有显示出强吸收特征，反演结果支持多云模式，排除了3.0σ置信度的晴朗大气。我们也把一个保守的上限钠丰度的替代方案下，一个明确的气氛。这是LRG-BEASTS（使用透射光谱的低分辨率地基系外行星大气调查）调查中的第八颗行星，该调查使用NTT等4 m级望远镜获得热彗星的低分辨率透射光谱，精度约为一个大气尺度高度。
We have performed low-resolution ground-based spectroscopy of HATS-46 b in transmission, using the EFOSC2 instrument on the ESO New Technology Telescope (NTT). HATS-46 b is a highly inflated exoplanet that is a prime target for transmission spectroscopy, having a Jupiter-like radius (0.95RJup) but a much lower mass (0.16MJup). It orbits a G-type star with a 4.7 d period, giving an equilibrium temperature of 1100 K. We observed one transit of HATS-46 b with the NTT, with the time-series spectra covering a wavelength range of 3900–9000 Å at a resolution(R)of ∼380. We achieved a remarkably precise transmission spectrum of 1.03 × photon noise, with a median uncertainty of 357 ppm for ∼200 Å-wide bins, despite the relative faintness of the host star withVmag= 13.6. The transmission spectrum does not show strong absorption features and retrievals favour a cloudy model, ruling out a clear atmosphere with 3.0σ confidence. We also place a conservative upper limit on the sodium abundance under the alternative scenario of a clear atmosphere. This is the eighth planet in the LRG-BEASTS (Low-Resolution Ground-Based Exoplanet Atmosphere Survey using Transmission Spectroscopy) survey, which uses 4 m-class telescopes such as the NTT to obtain low-resolution transmission spectra of hot Jupiters with precisions of around one atmospheric scale height.