发表机构
Chalmers University of Technology; Université libre de Bruxelles; KU Leuven（查尔姆斯理工大学; 布鲁塞尔自由大学; 荷语鲁汶大学）
机构由 AI 辅助整理，请以论文原文为准。AI 中文总结
通过光谱监测在J型碳星VZ Per和UV Cam中发现长次周期变星，视向速度周期分别约960天和1178天，支持低质量伴星的双星模型，并揭示气体尘埃随相位变化。
AI 中文摘要
长次周期（LSP）变星是长周期变星的一个子类，其起源尚存争议。J型碳星是富含13C的碳星子类，这种化学特异性的起源尚不清楚。本文报告了在两颗J型碳星VZ Per和UV Cam中发现LSP。方法：利用长达十年的光谱监测，获得了两颗星的长期视向速度曲线。通过频率分析，我们分离出LSP信号。将得到的周期性变化与光谱轮廓的变化以及已有的光变曲线进行比较，以进一步约束调制的起源。结果：对于VZ Per，从视向速度曲线（约960天）得出的LSP与光变曲线变暗事件以及Balmer吸收线轮廓的变化相关。这些结果转化为气体和尘埃柱密度随LSP相位的变化，最大气体柱密度出现在尘埃之前。对于UV Cam，视向速度监测得出约1178天的周期，振幅约为1 km/s。将视向速度调制解释为两颗星的开普勒信号，发现存在一个低质量（<0.1太阳质量）的近距离伴星。在这种情景下，气体和尘埃柱密度随（轨道）相位的变化追踪了亚恒星伴星后方膨胀的彗星状尾迹中的物质。结论：这些观测提供了LSP变星中气体和尘埃随时间的变化，这与当前的双星情景一致。此外，在J型碳星中检测到LSP，将其当前的演化状态锚定在热脉冲AGB阶段产生尘埃的区域。
英文摘要
Long-secondary-period (LSP) variables are a subclass of long-period variables whose origin is a matter of debate. J-type carbon stars are a subclass of carbon stars enriched in 13C, and the origin of this chemical peculiarity is unclear. In this paper, we report on the discovery of a LSP in two J-type carbon stars: VZ Per and UV Cam. Methods. A decade-long spectroscopic monitoring was used to obtain a long-term radial-velocity curve for the two stars. From a frequency analysis, we isolated a LSP signal. The retrieved periodicity was then compared with changes in spectral profiles and available light-curve variability to further constrain the origin of the modulation. Results. For VZ Per, the LSP derived from the radial-velocity curve (~960 days) is correlated with the light-curve dimming event and a variation in the Balmer absorption line profile. These results translate into changes in the gas and dust column densities with the phase of the LSP, with the maximum gas column density occurring ahead of the dust. For UV Cam, the radial velocity monitoring yields a period of ~1178 d with an amplitude of about 1 km/s. Interpreting the RV modulation as a Keplerian signal for both stars, a low-mass (<0.1Msun) close companion is found. In this scenario, variations in gas and dust column densities with (orbital) phase trace the material in the expanding comet-like tail trailing the substellar companion. Conclusions. These observations provide time-dependent variations of the gas and dust in LSP variables that are consistent with the current binary scenario. Furthermore, the detection of LSP among J-type carbon stars anchors their current evolutionary status in the dust-producing region of the thermally-pulsing AGB phase.
CommentsIn press
