AI 中文总结
研究红超巨星 HD 216946 长周期径向速度变化起源，通过分析 RV 数据、LPV、色球活动指标及光度变化，发现其变化与多种因素有关，多个不同周期共存，表明是多周期红超巨星，变化可能由色球活动等主导，伴星存在不能完全排除。
AI 中文摘要
我们展示了使用 Bohyunsan 光学天文台阶梯光谱仪（BOES）在约 22 年时间内对 K 型红超巨星 HD~216946（V424 Lac）进行的精确径向速度（RV）观测。RV 测量揭示了一个周期为 1365 天的显著长周期变化。为探究其起源，我们将 RV 数据与谱线轮廓变化（LPV）、色球活动指标及已发表的光度变化一起分析。LPV 周期约为 1370 - 1380 天，钠 D 线在 1355 天附近有类似周期，均与 RV 周期相当；H 线指标周期为 2730 - 2800 天，约为 RV 周期两倍。RV 变化与活动相关诊断的紧密对应强烈表明，1365 天的 RV 信号主要与色球活动和扩展的大气变化有关，而非纯粹的开普勒运动。已发表的光度研究还报告了额外的长周期变化，包括一个 1601 天的类似长次周期（LSP）的变化。多个不同周期的共存表明，HD~216946 观测到的变化不太可能源于单一物理机制。因此，我们将 HD~216946 解释为一个多周期红超巨星，其中几种内在恒星过程共存。观测到的变化很可能主要由色球活动和大规模大气动力学主导，可能伴有旋转调制和类似 LSP 的变化，尽管不能完全排除低质量恒星伴星的存在。
英文摘要
We present precise radial-velocity (RV) observations of the K-type red supergiant HD~216946 (V424 Lac) obtained over approximately 22 years with the Bohyunsan Optical Astronomy Observatory Echelle Spectrograph (BOES). The RV measurements reveal a significant long-period variability with a period of 1365 days. To investigate its origin, we analyzed the RV data together with line-profile variations (LPVs), chromospheric activity indicators, and published photometric variability. The LPVs exhibit periods of approximately 1370--1380 days, while the Na~D lines show a similar periodicity near 1355 days, both comparable to the RV period. In contrast, the H-line indicators display longer periods of 2730--2800 days, approximately twice the RV period. The close correspondence between the RV variations and the activity-related diagnostics strongly suggests that the 1365-day RV signal is primarily linked to chromospheric activity and extended atmospheric variability rather than arising from purely Keplerian motion. Published photometric studies also report additional long-period variability, including a 1601-day long secondary-period (LSP)-like variation. The coexistence of multiple non-identical periods indicates that the observed variability of HD~216946 is unlikely to originate from a single physical mechanism. We therefore interpret HD~216946 as a multiperiodic red supergiant in which several intrinsic stellar processes coexist. The observed variability is most likely dominated by chromospheric activity and large-scale atmospheric dynamics, possibly accompanied by rotational modulation and LSP-like variability, although the presence of a low-mass stellar companion cannot be completely excluded.
Comments8 pages, 4 figures, accepted in JKAS
