Variable and Supersonic Winds in the Atmosphere of an Ultrahot Giant Planet
Variable and Supersonic Winds in the Atmosphere of an Ultrahot Giant Planet
复制标题
超热巨行星大气层中的变速风和超音速风
DOI：
10.3847/1538-3881/ac51d2
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发表时间：
2022
期刊：
影响因子：
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通讯作者：
K. Strassmeier
中科院分区：
文献类型：
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作者：
Anusha Pai Asnodkar;J. Wang 王;J. Eastman;P. Cauley;B. Gaudi;I. Ilyin;K. Strassmeier
热彗星（HJ）从它们的恒星宿主那里接受强烈的辐射。由此产生的大气极端环境使我们能够研究驱动行星大气动力学的条件，例如，全球范围的风大气环流模式预测了昼夜风和赤道急流，速度约为几公里秒-1。为了测试这些模型，我们应用高分辨率透射光谱学使用波茨坦Echelle偏振和光谱仪（PEPSI）光谱仪的大型双目望远镜研究大气层的KELT-9 B，超热木星和目前已知的最热的行星。我们测量了由地球大气中的Fe ii特征跟踪的10 km s-1昼夜风。这与先前的文献（包括使用PEPSI获得的数据）不一致，该文献报告KELT-9 B上没有明显的日侧风。我们确定这种差异的原因是由于在以前的文献中KELT-9 B的星历不准确。我们更新了星历表，它将之前数据集的中天时间偏移了10分钟，从而在这里分析的所有数据集中一致地检测到蓝移。此外，与北方半球高精度径向速度行星搜索器的档案数据集的比较表明，在数周到数年的时间尺度上，风的时间变化为0.5 -8 km s-1。大气动力学在HJ上的时间变化是某些大气环流模式所预测的一种现象，迄今为止在这些时间尺度上还没有观察到。然而，我们在KELT-9 B上测量的如此大的变化对大气环流模型提出了挑战，该模型预测的风变化幅度在几天到几周的时间尺度上要低得多。
Hot Jupiters (HJs) receive intense irradiation from their stellar hosts. The resulting extreme environments in their atmospheres allow us to study the conditions that drive planetary atmospheric dynamics, e.g., global-scale winds. General circulation models predict day-to-nightside winds and equatorial jets with speeds of the order of a few km s−1. To test these models, we apply high-resolution transmission spectroscopy using the Potsdam Echelle Polarimetric and Spectroscopic Instrument (PEPSI) spectrograph on the Large Binocular Telescope to study the atmosphere of KELT-9 b, an ultrahot Jupiter and currently the hottest known planet. We measure ∼10 km s−1 day-to-nightside winds traced by Fe ii features in the planet’s atmosphere. This is at odds with previous literature (including data taken with PEPSI), which report no significant day-to-nightside winds on KELT-9 b. We identify the cause of this discrepancy as due to an inaccurate ephemeris for KELT-9 b in previous literature. We update the ephemeris, which shifts the midtransit time by up to 10 minutes for previous data sets, resulting in consistent detections of blueshifts in all the data sets analyzed here. Furthermore, a comparison with archival data sets from the High-accuracy Radial velocity Planet Searcher for the Northern hemisphere suggests a temporal wind variability of ∼5–8 km s−1 over timescales between weeks to years. Temporal variability of atmospheric dynamics on HJs is a phenomenon anticipated by certain general circulation models that has not been observed over these timescales until now. However, such large variability as we measure on KELT-9 b challenges general circulation models, which predict much lower amplitudes of wind variability over timescales between days to weeks.
DOI：
10.3847/2041-8213/ac0fec
发表时间：
2021
期刊：
The Astrophysical Journal Letters
影响因子：
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作者：
Hindle A
通讯作者：
Hindle A