The availability of multi-wavelength observations and parallaxes from the space missions and very comprehensive models of AGB evolution that include the accretion of matter from the circumbinary disc have strongly impacted our understanding of these enigmatic objects. The important developments made in the recent times are summarized here. The revised estimates of luminosities (derived from better-defined Spectral Energy Distributions (SEDs) and new distances from Gaia DR2) further support the opinion that RV Tauri stars contain a mixture of post-AGB stars and post-RGB stars. Their locations in HR diagram also indicate that the instability strip (IS) of RV Tauri stars have a broader extension in the cooler edge than that of classical Cepheids. A new P−L relation has been calibrated for the galactic Cepheids which have a steeper slope than that derived for the Population II Cepheids and RV Tauri stars in Magellanic clouds . The most significant chemical peculiarity exhibited by RV Tauri stars and other post-AGB stars is the selective depletion of refractory elements that correlates with their condensation temperatures. A large range in the size of depletion as well as in the shapes of the depletion curves has been observed. Earlier models to explain this effect were mostly qualitative. Recent investigators model these depletions using evolutionary codes (e.g. MESA) to evolve stars in the post-AGB phase, while including accretion of metal-poor gas from circumbinary disc. These authors model the accretion rate onto a the binary post-AGB star from a viscously evolving disc for a range of initial accretion rates and disc masses. It is reported that large initial accretion rates and disc masses are required to explain the large depletion and saturated depletion curve that could extend the evolution time of post-AGB star. It is also proposed that the unsaturated depletion curve (with a plateau) are likely to be caused by post-RGB stars.

中文翻译：

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RV Tauri 恒星的最新进展

来自太空任务的多波长观测和视差的可用性以及非常全面的 AGB 演化模型（包括从环绕双星盘中吸积物质）强烈影响了我们对这些神秘物体的理解。这里总结了最近取得的重要进展。修正后的光度估计值（源自更明确的光谱能量分布 (SED) 和与盖亚 DR2 的新距离）进一步支持 RV Tauri 恒星包含后 AGB 恒星和后 RGB 恒星的混合物的观点。它们在 HR 图中的位置还表明，RV Tauri 恒星的不稳定带 (IS) 在较冷的边缘具有比经典造父变星更宽的延伸。已为银河系造父变星校准了新的 P-L 关系，其斜率比从麦哲伦云中的星族 II 造父变星和 RV 金牛座恒星推导出的斜率更陡。RV Tauri 星和其他后 AGB 星表现出的最重要的化学特性是与冷凝温度相关的难熔元素的选择性消耗。已经观察到耗尽的大小以及耗尽曲线的形状的大范围。解释这种影响的早期模型大多是定性的。最近的研究人员使用演化代码（例如 MESA）对这些损耗进行建模，以在 AGB 后阶段演化恒星，同时包括来自环双星盘的贫金属气体的吸积。这些作者针对一系列初始吸积率和盘质量，模拟了从粘性演化盘到双星后 AGB 恒星的吸积率。据报道，需要大的初始吸积率和盘质量来解释可能延长后 AGB 恒星演化时间的大消耗和饱和消耗曲线。还提出不饱和耗尽曲线（具有平台）可能是由后 RGB 恒星引起的。