The Bright Star in the globular cluster 47 Tucanae (NGC 104) is a post-asymptotic giant branch (post-AGB) star of spectral type B8 III. The ultraviolet spectra of late-B stars exhibit myriad absorption features, many due to species unobservable from the ground. The Bright Star thus represents a unique window into the chemistry of 47 Tuc. We have analyzed observations obtained with the Far Ultraviolet Spectroscopic Explorer, the Cosmic Origins Spectrograph aboard the Hubble Space Telescope, and the Magellan Inamori Kyocera Echelle Spectrograph on the Magellan Telescope. By fitting these data with synthetic spectra, we determine various stellar parameters (T _eff = 10,850 250 K, ) and the photospheric abundances of 26 elements, including Ne, P, Cl, Ga, Pd, In, Sn, Hg, and Pb, which have not previously been published for this cluster. Abundances of intermediate-mass elements (Mg through Ga) generally scale with Fe, while the heaviest elements (Pd through Pb) have roughly solar abundances. Its low C/O ratio indicates that the star did not undergo third dredge-up and suggests that its heavy elements were made by a previous generation of stars. If so, this pattern should be present throughout the cluster, not just in this star. Stellar-evolution models suggest that the Bright Star is powered by a He-burning shell, having left the AGB during or immediately after a thermal pulse. Its mass (0.54 0.16M _⊙) implies that single stars in 47 Tuc lose 0.1–0.2 M _⊙ on the AGB, only slightly less than they lose on the red giant branch.

球状星团 47 Tucanae (NGC 104) 中的亮星是一颗光谱类型为 B8 III 的渐近巨星分支 (post-AGB) 恒星。晚 B 星的紫外光谱显示出无数的吸收特征，其中许多是由于从地面无法观测到的物种。因此，明亮之星代表了了解 47 Tuc 化学的独特窗口。我们分析了用远紫外光谱探测器、哈勃太空望远镜上的宇宙起源光谱仪和麦哲伦望远镜上的麦哲伦稻盛京瓷阶梯光谱仪获得的观测结果。通过将这些数据与合成光谱拟合，我们确定了各种恒星参数（T _eff = 10,850 250 K，) 和 26 种元素的光球丰度，包括 Ne、P、Cl、Ga、Pd、In、Sn、Hg 和 Pb，这些元素之前尚未针对该星团发表。中等质量元素（Mg 到 Ga）的丰度通常与 Fe 成比例，而最重的元素（Pd 到 Pb）大致具有太阳丰度。它的低 C/O 比表明这颗恒星没有经历第三次疏浚，并表明它的重元素是由上一代恒星制造的。如果是这样，这种模式应该存在于整个星团中，而不仅仅是在这颗恒星中。恒星演化模型表明，明亮之星由燃烧氦的壳提供动力，在热脉冲期间或之后立即离开 AGB。它的质量 (0.54 0.16 M _⊙ ) 意味着 47 Tuc 中的单颗恒星损失 0.1-0.2 M _⊙在AGB上，只比他们在红巨星分支上的损失略少。