恒星活动与行星效应会引发视向速度（RV）偏移，并导致恒星线轮廓的形状产生时间畸变。因此，精确探测恒星线轮廓可提供大量与恒星本身及其所有轨道行星相关的信息。通常，互相关函数（Cross-Correlation Functions, CCFs）被用作恒星线轮廓的替代表征。然而，CCFs的形状会因线混合与混叠而发生畸变，限制了可从中探测的恒星与行星物理信息。最小二乘反卷积（Least-squares deconvolution, LSD）提供了另一种方案，它可直接拟合光谱的平均线轮廓以生成高精度轮廓。本文提出了我们的新方法ACID（精确连续谱拟合与反卷积，Accurate Continuum fItting and Deconvolution），该方法基于LSD技术，可同时拟合光谱连续谱与线轮廓，并在有效光深度维度执行LSD。在模型数据上的测试表明，ACID能够精确识别并校正光谱连续谱，以反演注入的线轮廓。我们还将ACID应用于HD189733b凌星期间获取的HARPS存档数据。将重载版Rossiter-McLaughlin技术分别应用于ACID轮廓与HARPS CCFs的结果显示，与CCFs相比，ACID的残差轮廓将线外均方根（RMS）提升了5%以上。此外，研究表明ACID轮廓呈现出Voigt轮廓形状，能更好地描述恒星线轮廓的预期形状。这种改进的表征效果说明，对于慢自转恒星，ACID能更好地保留编码在恒星线轮廓形状中的恒星与行星物理信息。
英文摘要：
Stellar activity and planetary effects induce radial velocity (RV) offsets and cause temporal distortions in the shape of the stellar line profile. Hence, accurately probing the stellar line profile offers a wealth of information on both the star itself and any orbiting planets. Typically, Cross-Correlation Functions (CCFs) are used as a proxy for the stellar line profile. The shape of CCFs, however, can be distorted by line blending and aliasing limiting the stellar and planetary physics that can be probed from them. Least-squares deconvolution (LSD) offers an alternative that directly fits the mean line profile of the spectrum to produce a high-precision profile. In this paper, we introduce our novel method ACID (Accurate Continuum fItting and Deconvolution) that builds on LSD techniques by simultaneously fitting the spectral continuum and line profile as well as performing LSD in effective optical depth. Tests on model data revealed ACID can accurately identify and correct the spectral continuum to retrieve an injected line profile. ACID was also applied to archival HARPS data obtained during the transit of HD189733b. The application of the Reloaded Rossiter-McLaughlin technique to both ACID profiles and HARPS CCFs shows ACID residual profiles improved the out-of-line RMS by over 5% compared to CCFs. Furthermore, ACID profiles are shown to exhibit a Voigt profile shape that better describes the expected profile shape of the stellar line profile. This improved representation shows that ACID better preserves the stellar and planetary physics encoded in the stellar line profile shape for slow rotating stars.
ExoJAX Retrievals of VLT/CRIRES Spectra of Luhman 16AB: C/O Ratios and Systematic Uncertainties
Osaka University（大阪大学）；Kyoto University（京都大学）；Institute of Space and Astronautical Science, Japan Aerospace Exploration Agency（日本宇宙航空研究开发机构宇宙科学研究所）；The University of Tokyo（东京大学）
On the impact of the vertical structure of Martian water ice clouds on nadir atmospheric retrievals from simultaneous EMM/EXI and TGO/ACS-MIR observations
Relative abundance constraints from high-resolution optical transmission spectroscopy of WASP-121b, and a fast model-filtering technique for accelerating retrievals
