AI 中文总结
研究利用盖亚 DR3 光曲线傅里叶参数确定经典造父变星铁丰度，通过截断傅里叶级数建模提取参数，用复制随机森林算法选择特征，经线性回归校准多变量关系，应用于多星系样本验证其可靠性。
AI 中文摘要
估计经典造父变星（CCs）的铁丰度（[Fe/H]）对于通过周光关系验证宇宙距离尺度以及追踪年轻恒星群体的化学演化至关重要。然而，标准光谱测定非常耗时，限制了其对大样本或远距离样本的应用。本文通过研究从盖亚任务测光中导出的光曲线傅里叶参数是否可作为[Fe/H]的可靠代理，提供了一种实用的多波段替代方法。我们的参考样本包括来自盖亚 DR3 的 398 颗基模 CCs，其具有文献中可用的高分辨率光谱金属丰度，涵盖广泛的脉动周期。对 G、G_BP 和 G_RP 波段的光曲线用截断傅里叶级数进行建模，以提取特征振幅、振幅比和相位差。我们实施了复制随机森林算法作为特征选择工具，以基于节点纯度的总增加来分离最具预测性的参数。使用选定的特征，我们通过线性回归校准了一个经验多变量关系，纳入高阶多项式项以捕捉复杂的形态依赖性。主要的未加权 OLS 模型产生的残余均方根为 0.213 dex，皮尔逊相关系数为 0.61。作为外部有效性检查，我们将此校准应用于银河系、大麦哲伦星系和小麦哲伦星系中 CCs 的大目标样本。所得的光度金属丰度分布正确地再现了三个星系预期的化学富集历史和峰值，证明了这种关系在盖亚 DR4 时代用于群体研究的可靠性。
英文摘要
Estimating the iron abundance ([Fe/H]) of Classical Cepheids (CCs) is crucial both for validating the cosmic distance scale through the Period-Luminosity relation and for tracing the chemical evolution of young stellar populations. However, standard spectroscopic determinations are highly time-consuming, limiting their application to large or distant samples. This work delivers a practical, multi-band alternative by investigating whether light-curve Fourier parameters derived from Gaia mission photometry can serve as reliable proxies for [Fe/H]. Our reference sample comprises 398 fundamental-mode CCs from Gaia DR3 with high-resolution spectroscopic metallicities available in the literature, spanning a wide range of pulsation periods. Light curves in the G, G_BP, and G_RP bands were modeled with a truncated Fourier series to extract characteristic amplitudes, amplitude ratios, and phase differences. We implemented a replicated Random Forest algorithm as a feature selection tool to isolate the most predictive parameters based on their total increase in node purity. Using the selected features, we calibrated an empirical, multi-variable relation via linear regression, incorporating higher-order polynomial terms to capture complex morphological dependencies. The primary unweighted OLS model yields a residual rms of 0.213 dex and a Pearson correlation of 0.61. As an external validity check, we applied this calibration to large target samples of CCs in the Milky Way, LMC, and SMC. The resulting photometric metallicity distributions correctly reproduce the expected chemical enrichment history and peak values of the three galaxies, proving the reliability of this relation for population studies in the Gaia DR4 era.
CommentsAccepted for publication in Astronomy & Astrophysics
