发表机构
University of Warsaw; University of Wrocław; California Institute of Technology（华沙大学; 弗罗茨瓦夫大学; 加州理工学院）
机构由 AI 辅助整理，请以论文原文为准。AI 中文总结
本研究在约80年光变数据中发现CZ Tuc星存在与长周期次周期比值约8的55.47天脉动，判定为潮汐激发振荡，首次为LSP变星的双星假说提供独立观测证据。
AI 中文摘要
长周期次周期（LSP）在约三分之一的脉动红巨星中被观测到，尽管经过数十年的研究仍无法解释，双星假说和非径向振荡是主要的竞争假说。如果 LSP 变星确实是相互作用的偏心双星系统，由红巨星和亚恒星天体组成，那么预计其中一部分会出现潮汐激发振荡（TEO）。因此，探测 TEO 为双星假说提供了一个独立的检验，此前尚未应用于 LSP 星。利用由哈佛大学数字天空访问（DASCH）、Hipparcos 和全天自动巡天（ASAS）测光数据组合而成的约 80 年光变曲线，我们发现 CZ 杜鹃座（CZ Tuc）除了其 443.62±0.12 天的 LSP 外，还存在一个 55.4734±0.0074 天的脉动周期，两者比值为 7.9970±0.0024，与 TEO 一致。理论模型表明，在采用 CZ Tuc 的估计基本参数后，候选 TEO 的观测振幅可以被产生。我们的发现将 CZ Tuc 确定为第一颗具有 TEO 的候选 LSP 星，为至少一部分这些神秘变星的双星性质提供了独立证据。
英文摘要
Long secondary periods (LSPs), observed in about one-third of pulsating red giants, remain unexplained despite decades of study, with binarity and non-radial oscillations as the leading competing hypotheses. If LSP variables are indeed interacting, eccentric binary systems consisting of a red giant and a substellar object, tidally excited oscillations (TEOs) would be expected to appear in a fraction of them. Therefore, detection of TEOs offers an independent test of the binary scenario that has not previously been applied to LSP stars. Using a combined, approximately 80-year light curve assembled from Digital Access to a Sky Century @ Harvard (DASCH), Hipparcos, and All Sky Automatic Survey (ASAS) photometry, we find that CZ Tucanae (CZ Tuc) exhibits a pulsation period of $55.4734\pm0.0074$ days along with its LSP of $443.62\pm0.12$ days, with a ratio of $7.9970\pm0.0024$ - consistent with a TEO. Theoretical models show the observed amplitude of the candidate TEO could be produced after adopting the estimated fundamental parameters of CZ Tuc. Our findings identify CZ Tuc as the first candidate LSP star with a TEO, providing independent evidence for binarity among at least a subset of these enigmatic variables.
Comments15 pages, 9 figures, 1 table. Submitted to AAS Journals
