Yonsei Evolutionary Population Synthesis (YEPS) Model. III. Surface Brightness Fluctuation of Normal and Helium-enhanced Simple Stellar Populations

摘要: 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 normal-He agrees with other existing models, He-rich population, containing hotter horizontal-branch stars brighter red-clump than entails a substantial change in SSPs. show that magnitudes are affected by at least $\sim$0.3~mag even $I$- near-IR bands given colors, from which SBF-based distances often derived. Due to uncertainties both observations however, SBFs Galactic globular clusters early-type galaxies do not allow verifying model. propose when combined independent metallicity age indicators such as ${\rm Mg}_2$ H}\beta$, UV optical can readily detect underlying unresolved systems distance out $\gtrsim 20$\,Mpc. A full set spectro-photometric data SSPs Yonsei Evolutionary Population Synthesis (YEPS) is available download this http URL.