We perform an asteroseismic investigation of giant stars in the field of NGC 6791 with previous indications of atypical evolution. The analysis uses observations from Kepler and Gaia in combination with ground-based photometry, a literature radial-velocity study, and measurements of eclipsing binaries in the cluster. We derive mass, radius, effective temperature, evolutionary stage, and apparent distance modulus of each target. Among the investigated cluster giants we find clear evidence of overmassive and undermassive members, and non-members with strong hints of potential past membership. Our results indicate that about 10 per cent of the red giants in the cluster have experienced mass transfer or a merger. High-resolution high-S/N spectroscopic follow-up could confirm potential past membership of the non-members, and reveal whether certain element abundances might expose the non-standard evolution of overmassive and undermassive stars. If so, field stars of similar type could be identified as what they are, i.e. overmassive or undermassive stars, and not mistakenly classified as younger or older than they are.

中文翻译：

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疏散星团 NGC 6791 的超大质量、小质量和潜在过去成员的星震学

我们对 NGC 6791 领域的巨星进行了星震调查，之前有非典型演化的迹象。该分析结合了开普勒和盖亚的观测结果以及基于地面的光度测量、文献径向速度研究以及星团中食双星的测量。我们推导出每个目标的质量、半径、有效温度、演化阶段和表观距离模量。在被调查的星团巨人中，我们发现了超大和超小成员的明确证据，以及具有潜在过去成员身份的强烈暗示的非成员。我们的研究结果表明，星团中约 10% 的红巨星经历了质量转移或合并。高分辨率高信噪比光谱跟踪可以确认非成员的潜在过去成员资格，并揭示某些元素丰度是否可能揭示超大质量和小质量恒星的非标准演化。如果是这样，类似类型的场星可以被识别为它们是什么，即质量过大或质量过小的恒星，并且不会被错误地归类为比它们年轻或年老。