对北天极恒星周围系外行星的搜索X. 演化恒星HD 216595径向速度变化的起源
A Search for Exoplanets around Northern Circumpolar Stars X. The origin of radial velocity variations in the evolved star HD 216595
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中文总结 AI 辅助
研究AGB恒星HD 216595长周期、低振幅径向速度变化起源，利用约16年高分辨率光谱数据，发现567天周期性信号，与恒星活动指标无强关联，RV变化可能源于恒星固有过程，后续需改进诊断和建模区分信号。
中文摘要 AI 辅助
探测演化恒星，特别是渐近巨星分支（AGB）恒星周围的行星伴星具有挑战性，因为恒星的固有变异性，如表面对流、脉动和质量损失，会产生类似开普勒运动的径向速度（RV）信号。我们基于用보현산光学天文台阶梯光谱仪（BOES）和拉斯坎布雷斯天文台机器人阶梯光谱仪网络（NRES）仪器获得的约16年的高分辨率光谱数据，研究了在AGB恒星HD 216595中观测到的长周期、低振幅RV变化的起源。RV测量揭示了一个在567天具有统计学显著意义的周期性信号，该信号可用与次恒星伴星一致的开普勒模型来描述。然而，在RV变化与恒星活动指标之间未发现强相关性，尽管在某些诊断中存在相似时间尺度的微弱信号。鉴于HD 216595的恒星特性以及与先前报道案例的相似性，观测到的RV变化可能与恒星固有过程有关，尽管不能完全排除伴星引起的起源。进一步的进展需要改进诊断和更复杂的模型来区分恒星变异性与真正的轨道信号。
英文摘要
Detecting planetary companions around evolved stars, particularly asymptotic giant branch (AGB) stars, is challenging due to intrinsic stellar variability such as surface convection, pulsations, and mass loss, which can produce radial velocity (RV) signals that mimic Keplerian motion. We investigate the origin of long-period, low-amplitude RV variations observed in the AGB star HD 216595 based on high-resolution spectroscopic data spanning approximately 16 years obtained with the Bohyunsan Optical Astronomy Observatory Echelle Spectrograph (BOES) and the Las Cumbres Observatory Network of Robotic Echelle Spectrographs (NRES) instruments. The RV measurements reveal a statistically significant periodic signal at 567 days that can be described by a Keplerian model consistent with a substellar companion. However, no strong correlations are found between the RV variations and stellar activity indicators, including line bisectors, chromospheric activity, and photometric variability, although weak signals at similar timescales are present in some diagnostics. Given the stellar properties of HD 216595 and similarities to previously reported cases, the observed RV variations are likely related to intrinsic stellar processes, although a companion-induced origin cannot be definitively ruled out. Further progress will require improved diagnostics and more sophisticated modeling to disentangle stellar variability from genuine orbital signals.
