Multiple Stellar Populations of Globular Clusters from Homogeneous Ca–CN–CH–NH Photometry. VII. Metal-poor Populations in 47 Tucanae (NGC 104)* †

Abstract We present new large field-of-view (∼1°×1°) Ca-CN photometry of the prototypical metal-rich globular cluster 47 Tucanae (NGC 104). Our results are following. (1) The populational number ratios red giant branch (RGB) and horizontal (RHB) in excellent agreement: n (CN-w): (CN-s) = 30:70 (±1–2), where CN-w CN-s stand for CN-weak CN-strong populations, respectively. Both RGB RHB populations more centrally concentrated than those are. (2) photometric metallicities individual stars each population can be well described by bimodal distributions with two metallicity peaks, [Fe/H] ∼−0.72 −0.92 dex, metal-poor components occupy ∼13% total stars. significantly showing a similar result that we found M3. (3) bump V magnitudes indicate there is no difference helium abundance between while enhancement Δ Y ∼0.02–0.03 required populations. (4) morphology Tuc appears to support our idea distribution cluster. suggest could another example merger remnants clusters, M3 M22.