TILARA：一种无需模板的逐线算法用于径向速度分析。I. 代码描述及在类太阳恒星上的应用
TILARA: Template-Independent Line-by-line Algorithm for Radial velocity Analysis. I. Description of the code and application on a Sun-like star
AI总结：
本文提出TILARA算法，通过逐线方法计算径向速度，无需模板，适用于光谱模板构建不推荐的情况，应用于HD 102365的520次ESPRESSO观测，验证其性能。
摘要：
精确的径向速度（RVs）通常通过相关性或模板匹配方法获得，但这些方法依赖参考光谱，当数据变化、受污染或采样稀疏时可能引入偏差。逐线方法提供了一种替代计算RVs的方式，但通常仍依赖模板创建，因此存在固有局限。我们引入TILARA，一种无需模板的逐线RV提取代码，旨在允许我们计算逐线RVs，并在光谱模板构建不推荐时有效运行。虽然最初受未来PoET盘解析太阳观测的启发，TILARA被设计为能够适应不同恒星光谱类型和仪器。一个经过挑选的单个吸收线列表被用作参考，通过ARES中的高斯拟合自动测量线中心。然后，利用参考线列表和ARES在目标恒星光谱上测量的线，TILARA计算RVs，并通过sigma-clipping或下权重方法应用可配置的异常值剔除。我们测试了代码的不同配置、RV不确定性估计方法和线选择标准。该代码应用于520次ESPRESSO观测的类太阳恒星HD 102365，以评估其性能。TILARA随后与其他RV提取方法进行了测试。在sigma-clipping和down-weighting模式下，TILARA提供的RV时间序列的标准差和误差棒与采用不同方法的传统方法得出的结果相似。
英文摘要：
Precise radial velocities (RVs) are commonly derived through cross-correlation or template-matching methods, both of which rely on a reference spectrum that can introduce biases when the data are variable, contaminated, or sparsely sampled. Line-by-line methods offer an alternative way to compute RVs but generally still rely on template creation and therefore share its inherent limitations. We introduce TILARA, a template-independent, line-by-line RV extraction code designed to allow us to derive line-by-line RVs and to operate effectively even when spectral template construction is not recommended. While originally motivated by future PoET disk-resolved solar observations, TILARA has been built with the flexibility to work with different stellar spectral types and instruments. A curated list of individual absorption lines is used as a reference to automatically measure line centers with via Gaussian fitting with ARES. Then, using the reference lines list, and the lines measured with ARES on the spectra of the target star, TILARA computes the RVs and applies configurable outlier rejection through sigma-clipping or down-weighting methods. We tested different configurations of the code, RV uncertainty estimation methods, and line selection criteria. The code was applied to 520 ESPRESSO observations of the Sun-like star HD 102365 to evaluate its performance. TILARA was then tested against other RV extraction methods. Both in its sigma-clipping and its down-weighting mode, TILARA provided resulting RV time-series with similar standard deviation and error bars as the ones derived using existing methods that follow different approaches.
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