Exploring the stellar surface phenomena of WASP-52 and HAT-P-30 with ESPRESSO
Exploring the stellar surface phenomena of WASP-52 and HAT-P-30 with ESPRESSO
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使用 ESPRESSO 探索 WASP-52 和 HAT-P-30 的恒星表面现象
DOI：
10.1051/0004-6361/202245523
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发表时间：
2023
影响因子：
6.5
通讯作者：
Cegla H
中科院分区：
文献类型：
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作者：
Cegla H
我们分析了用ESTERO、Eulercam和NGTS获得的两个目标的热彗星WASP-52 B和HAT-P30 B的光谱和光度跃迁，以及HAT-P-30的附加TESS数据。我们的目标是更新系统参数和完善我们的知识的主机星星表面。对于WASP-52来说，这颗伴星过去曾遮蔽过恒星黑子，因此我们的目标是使用重新加载的罗斯特-麦克劳克林技术直接探测其恒星黑子属性。不幸的是，我们在这里的数据集中没有发现星点掩星的证据。此外，我们还搜索了恒星表面的差异旋转（DR）和任何中心到边缘的变化（CLV）由于对流，但返回一个零检测。这对于WASP-52来说并不奇怪，因为它的温度相对较低，磁活动较高（导致CLV较低），并且预计的经度接近0 °（这意味着凌弦不太可能跨越几个恒星纬度）。对于HAT-P-30来说，这个结果更令人惊讶，因为它的有效温度更高，磁场更低，投影折射率更高（接近70 °）。为了探索HAT-P-30的零DR和CLV检测背后的原因，我们模拟了各种场景。我们发现，要么HAT-P-30上存在的CLV低于太阳能水平，要么DR的存在阻止了CLV检测，给出了本文中的数据的精度。DR和CLV都需要仔细处理，特别是对于具有高影响因子的系统，因为两者之间存在潜在的简并性。未来的观测和/或对数据中存在的红噪声（可能是由于颗粒化）进行复杂的处理，需要改进这些特定系统的DR和CLV;这样的观测也将提供另一个机会来尝试检查WASP-52上的星点。
We analyse spectroscopic and photometric transits of the hot Jupiters WASP-52 b and HAT-P30 b obtained with ESPRESSO, Eulercam and NGTS for both targets, and additional TESS data for HAT-P-30. Our goal is to update the system parameters and refine our knowledge of the host star surfaces. For WASP-52, the companion planet has occulted starspots in the past, and as such our aim was to use the reloaded Rossiter-McLaughlin technique to directly probe its starspot properties. Unfortunately, we find no evidence for starspot occultations in the datasets herein. Additionally, we searched for stellar surface differential rotation (DR) and any centre-to-limb variation (CLV) due to convection, but return a null detection of both. This is unsurprising for WASP-52, given its relatively cool temperature, high magnetic activity (which leads to lower CLV), and projected obliquity near 0° (meaning the transit chord is less likely to cross several stellar latitudes). For HAT-P-30, this result was more surprising given its hotter effective temperature, lower magnetic field, and high projected obliquity (near 70°). To explore the reasons behind the null DR and CLV detection for HAT-P-30, we simulated a variety of scenarios. We find that either the CLV present on HAT-P-30 is below the solar level or the presence of DR prevents a CLV detection given the precision of the data herein. A careful treatment of both DR and CLV is required, especially for systems with high impact factors, due to potential degeneracies between the two. Future observations and/or a sophisticated treatment of the red noise present in the data (likely due to granulation) is required to refine the DR and CLV for these particular systems; such observations would also present another opportunity to try to examine starspots on WASP-52.