We present an evolutionary population synthesis model of the surface brightness fluctuation (SBF) for normal and He-enriched simple stellar populations (SSPs). While our SBF model for the normal He population agrees with other existing models, the He-rich population, containing hotter horizontal branch stars and brighter red clump stars than the normal He population, entails a substantial change in the SBF of SSPs. We show that the SBF magnitudes are affected by He-rich populations at least ∼0.3 mag even in I - and near-infrared bands at given colors, from which the SBF-based distances are often derived. Due to uncertainties both in observations and models, however, the SBFs of Galactic globular clusters and early-type galaxies do not allow verifying the He-enriched model. We propose that when combined with independent metallicity and age indicators such as Mg 2 and H β , the UV and optical SBFs can readily detect underlying He-rich populations in unresolved...

中文翻译：

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延世进化种群综合（YEPS）模型。三，正常和氦增强的简单恒星种群的表面亮度波动

我们提出了正常和富含He的简单恒星种群（SSP）的表面亮度波动（SBF）的进化种群综合模型。虽然我们针对正常He人群的SBF模型与其他现有模型相符，但是富含He的人群（与正常He人群相比，其水平分支星和红色团块星更热）导致SSP的SBF发生了实质性变化。我们表明，即使在I和近红外波段的给定颜色下，SBF量也受至少约0.3 mag的He富集人口的影响，通常从中得出基于SBF的距离。然而，由于观测和模型都存在不确定性，银河系球状星团和早期类型星系的SBF不允许验证富含He的模型。