AI 中文总结
本研究构建T-GEX星表，对37颗类太阳恒星分类分析，识别出3个星群，发现约2/3为紫外异常恒星，探讨其对紫外超的潜在贡献。
AI 中文摘要
我们结合Gaia-ESO光谱数据、Gaia DR3天体测量数据、GALEX紫外测光数据以及2MASS和AllWISE红外测量数据，为37颗恒星构建了Tiny Gaia-ESO + GALEX（T-GEX）星表。天体测量和光谱质量筛选尽可能减少了明显的多星系统和光谱特殊性，不过无法排除未分辨的伴星。我们根据经验FGK型恒星紫外正常轨迹对这些恒星进行分类，在FUV-NUV与NUV-G平面应用了三组分高斯混合模型（GMM），对24颗恒星测量了Hα λ6563诊断量，并对3个紫外超星系进行了基于初始质量函数（IMF）的经验尺度计算。样本中约2/3的恒星为紫外异常恒星。GMM识别出3个星群：低温强紫外过剩星群（G1）、高温紫外正常星群（G2）和中间紫外过剩星群（G3）。G1占据狭窄的亚太阳金属丰度（[Fe/H]）范围，且α元素增强，具有最高的中位[Mg/Fe]；G3具有最高的中位[Fe/H]；G2的金属丰度范围最宽，中位年龄最年轻。G1和G3的年龄可延伸至老年，尽管它们的最年轻年龄估计受等时线简并性影响。在可用子样本中，增强的Hα核心发射仅出现在温度更高的G2恒星中，而G1中仅有1颗恒星有Hα覆盖。河外贡献高度依赖模板：中位G1模板最多可解释观测到的紫外输出的约20%，而如果约10%-15%的现存FGK型恒星共享最蓝的模板，则该模板可匹配大部分或全部NUV和FUV发射。
英文摘要
We constructed the Tiny Gaia-ESO + GALEX (T-GEX) catalogue by combining Gaia-ESO spectroscopy, Gaia DR3 astrometry, GALEX UV photometry, and 2MASS and AllWISE infrared measurements for 37 stars. Astrometric and spectroscopic quality cuts minimise obvious multiplicity and spectral peculiarity, although unresolved companions cannot be excluded. We classified the stars relative to the empirical FGK UV-normal locus, applied a 3-component Gaussian mixture model in the FUV-NUV versus NUV-$G$ plane, measured H$α$ $λ6563$ diagnostics for 24 stars, and performed an IMF-based empirical scaling calculation for three UV-upturn galaxies. Approximately 2/3 of the sample are UV-abnormal. The GMM identifies a cool, strongly UV-excess group (G1), a hotter UV-normal group (G2), and an intermediate UV-excess group (G3). G1 occupies a narrow, predominantly sub-solar [Fe/H] range and is $α$-enhanced, with the highest median [Mg/Fe]. G3 has the highest median [Fe/H], while G2 spans the broadest metallicity range and has the youngest median age. G1 and G3 extend to old ages, although their youngest estimates are affected by isochrone degeneracy. Enhanced H$α$ core emission occurs only among hotter G2 stars in the available subsample, but only one G1 star has H$α$ coverage. The extragalactic contribution is strongly template-dependent: the median G1 template accounts for at most $\sim20\%$ of the observed UV output, whereas the bluest template could match most or all of the NUV and FUV emission if shared by $\sim10$--$15\%$ of surviving FGK stars.
CommentsSubmitted to A&A; comments are welcome. Abstract abridged to meet arXiv's length limit. 14 pages, 6 figures, 3 tables
