AI 中文总结
本研究以蓝超巨星HD 14134为对象，结合5个月的光谱数据与TESS测光数据，分析其脉动信号与风变异性，发现~19.2天的g模式及其谐波，确认该星为演化向红超巨星的主序后天体，质疑其天鹅α型变星分类，强调长期多波段监测的必要性。
AI 中文摘要
大质量恒星的主序后演化包含显示高变异性的阶段，蓝超巨星便是这类天体之一，它们可能处于红超巨星演化前或后阶段，其变异性模式可为天体的恰当分类提供约束。本研究旨在表征B型超巨星HD14134的观测变异性，探究时变星风对恒星光变的影响及其对脉动信号可探测性的作用。研究人员收集了5个月的光谱数据并结合TESS测光数据，利用CMFGEN对时间平均光谱的建模及SED推导恒星参数，并用MESA计算的恒星演化模型验证；分析选定谱线的光变曲线与径向速度曲线以确定脉动信号，通过Hα线分析探究星风变异性及其对恒星光变的影响；使用GYRE脉动代码计算模式激发的预测结果，并与观测确定的频率对比。所有数据集均持续检测到周期约19.2天的g模式及其谐波，光谱揭示出强烈的非周期性星风变异性，并识别出3个由该星风变异性导致的频率信号。HD14134的恒星参数与年龄，以及无径向脉动的特征，将该星归类为向红超巨星阶段演化的主序后天体，质疑其天鹅α型变星的分类。研究结果表明，同步长期光谱与测光监测对于可靠的频率探测，以及区分时变星风与脉动产生的变异性是不可或缺的。
英文摘要
The post-main sequence (MS) evolution of massive stars encompasses phases in which the stars display high variability. One such class of objects are the blue supergiants which may be in either the pre- or post-red supergiant phase of their evolution. Their variability patterns might provide constraints for a proper classification of the objects. We aim to characterise the observed variability of the B supergiant HD14134 and to investigate the imprint of a time-variable wind on the brightness variation of the star and its impact on the detectability of pulsation signals. Spectroscopic data were collected over a 5-month period and combined with photometry from TESS. Stellar parameters were derived from modelling of the time-averaged spectrum with CMFGEN and the SED and were confirmed with stellar evolution models computed with MESA. The light curves and radial velocity curves of selected lines were analysed to determine pulsation signals. The wind variability and its imprint on the stellar brightness were investigated from an analysis of the Halpha line. Predictions of mode excitations were computed with the GYRE pulsation code and compared to the frequencies determined from the observations. A g-mode with a period of ~19.2 d and its harmonics are consistently detected in all data sets. The spectra unveil strong, non-periodic wind variability and 3 frequency signals were identified as due to this wind variability. The stellar parameters and age derived for HD14134 together with the absence of radial pulsations classify the star as a post-MS object evolving towards the red-supergiant stage, questioning its classification as alpha Cyg variable. The results reinforce that simultaneous long-term spectroscopic and photometric monitoring is indispensable for reliable frequency detections and for disentangling of variabilities imprinted by a time-variable wind from those imposed by pulsations.
Comments19 pages, including 19 figures and 8 tables. Accepted for publication in A&A
