AI 中文总结
研究三颗富碳早后渐近巨星阶段恒星中 CO 二次泛音线变化，通过高光谱分辨率观测，发现其强度、形状等在脉动周期有变化，线位置距系统速度不远，变化与恒星脉动联系或与激波有关。
AI 中文摘要
近红外 CO 分子线被认为与后渐近巨星阶段恒星的动力学过程有关，但尚未在高光谱分辨率下进行研究。本文给出了冷富碳后渐近巨星 IRAS 22272+5435、IRAS Z02229+6208 和 IRAS 20000+3239 在 H 波段的 CO 二次泛音线变化情况。观测到 CO 特征在脉动周期中强度、形状、径向速度发生变化，且在发射和吸收之间切换。CO 线位置始终距系统速度不超过约 10 km/s。三颗恒星的分子线变化在定性上相似，形成位点似乎是扩展大气。CO 线发射在接近光极大的脉动阶段往往最强，在接近光极小时往往最弱或出现吸收，类似于较短波长下 CN 红和 C₂天鹅系线的行为。分子线变化与恒星脉动的联系可能与每次脉动周期穿过大气的激波有关。
英文摘要
Near-infrared CO molecular lines are suggested to be linked with dynamic processes in post-AGB stars; however, they have not been investigated at high spectral resolution. CO second overtone line variability in the H-band is presented for the cool carbon-rich post-AGB stars IRAS 22272+5435, IRAS Z02229+6208, and IRAS 20000+3239. CO features are observed to change intensity, shape, and radial velocity as well as switch between emission and absorption during the pulsation cycle. At all times, the CO line positions are located no more than around 10 km/s away from the systemic velocity. Molecular line variation is qualitatively similar in all three stars, and it appears that the site of formation is the extended atmosphere. Emission in CO lines tends to be strongest during pulsation phases close to light maximum, and weakest emission or absorption tends to be seen when close to light minimum, resembling the behaviour in CN Red and C$_2$ Swan system lines at shorter wavelengths. The connection of molecular line variability with pulsation of the star could be related to a shock that traverses the atmosphere once per pulsation cycle.
Journal refThe Astrophysical Journal, 1006, 104 (2026)
