哈勃太空望远镜利用紫外观测对银河系内 48 个球状星团进行了分析，建立了迄今规模最大、最完整的蓝离群星样本，总数超过 3000 颗。这些星团形成于数十亿年前，但蓝离群星却表现得更炽热、更明亮、更年轻，长期以来被认为可能源于恒星碰撞或双星相互作用。新数据覆盖了从极低密度到极高密度的完整环境范围，为统计比较提供了坚实基础。

研究结果与长期预期相反：蓝离群星并未在最致密、最易发生碰撞的星团中最为常见。相反，它们在低密度星团中的数量显著更高，而在高密度环境中明显减少。这一分布趋势表明，环境密度与蓝离群星形成率呈负相关关系，而非正相关，否定了碰撞主导形成机制在整体上的主导地位。

进一步分析显示，蓝离群星与双星系统高度相关。在双星中，一颗恒星可通过吸积或并合获得额外燃料，从而“重置”演化时钟。但在高密度星团中，频繁的近距离引力相互作用会破坏双星，使其难以长期存活，双星数量因此下降，蓝离群星也随之减少。该研究首次以大样本统计方式清晰证明，蓝离群星主要是双星演化的产物，其数量受环境密度强烈调控，相关成果已发表于《自然·通讯》。

The Hubble Space Telescope used ultraviolet observations to analyze 48 globular clusters in the Milky Way, producing the largest and most complete sample of blue straggler stars to date, totaling more than 3000 objects. These clusters formed billions of years ago, yet blue stragglers appear hotter, brighter, and younger, long suspected to arise from either stellar collisions or binary interactions. The dataset spans the full range of cluster densities, from very sparse to extremely dense, enabling robust statistical comparisons.

Contrary to long-standing expectations, blue stragglers are not most abundant in the densest, most collision-prone clusters. Instead, they are significantly more common in low-density clusters and markedly fewer in high-density environments. This distribution shows a negative correlation between environmental density and blue straggler frequency, rather than a positive one, undermining the idea that stellar collisions are the dominant formation channel overall.

Further analysis shows that blue stragglers are tightly linked to binary star systems, where mass transfer or mergers can supply fresh fuel and effectively reset stellar aging. In dense clusters, frequent close encounters disrupt binaries before they can produce blue stragglers, reducing both binary survival and blue straggler numbers. This study provides the first clear large-sample evidence that blue stragglers are primarily products of binary evolution and that their abundance is strongly regulated by environmental density, with results published in Nature Communications.