In this work, we report the discovery of the rapidly evolving high-amplitude $δ$ Scuti star KIC 6382916 (J19480292+4146558) which is crossing the Hertzsprung gap. According to the analysis of the archival data, we find three independent pulsation modes, whose amplitudes and frequencies vary distinctly in 4 years. The linear period variation rates of the first two modes are about 3-4 times larger than the best seismic model constructed by the standard evolution theory, while that of the third one is about 8 times larger than the first two modes. What is more interesting is that, almost all the combinations of the third mode have frequency peaks $0.0815\ \mathrm{c\ d}^{-1}$ away from them in the frequency domain. A framework is proposed to interpret the markedly large frequency and amplitude variation rates of the third mode, in which we employ a new pulsation mode (resonating integration mode) generated by the resonance between a radial p-mode and a nonradial mixed mode. Moreover, a global analysis of the interactions between the three independent pulsation modes and their harmonics/combinations is performed based on the interaction diagrams of their amplitudes and phases, which would be a useful tool for the future asteroseismology research.
Asteroseismology of the High-amplitude $δ$ Scuti Star EH Librae
Institute for Frontiers in Astronomy and Astrophysics, Beijing Normal University(北京师范大学前沿天文与天体物理研究所);School of Physics and Astronomy, Beijing Normal University(北京师范大学物理与天文学院);Xinjiang Astronomical Observatory, Chinese Academy of Sciences(中国科学院新疆天文台);Department of Physics, Taiyuan Normal University(太原师范学院物理系);Institute of Computational and Applied Physics, Taiyuan Normal University(太原师范学院计算与应用物理研究所);School of Physics and Astronomy, China West Normal University(西华师范大学物理与天文学院);Yunnan Observatories, Chinese Academy of Sciences(中国科学院云南天文台);Key Laboratory for the Structure and Evolution of Celestial Objects, Chinese Academy of Sciences(中国科学院天体结构与演化重点实验室);International Centre of Supernovae, Yunnan Key Laboratory(云南省超新星国际研究中心);School of Physics, Nankai University(南开大学物理学院)
Unveiling $δ$ Scuti and $γ$ Doradus Hybrid Pulsation of HD 53166 and HD 53349 Plus Rich Frequencies in HD 52788 -- Catalogs of 70552 $δ$ Sct and 8080 $γ$ Dor
Determining the incidence rate of magnetic $δ$ Scuti candidates with CoRoT
DTU Space, Technical University of Denmark(丹麦技术大学空间中心);LIRA, Paris Observatory, CNRS, PSL University, Sorbonne University, Université Paris Cité, CY Cergy Paris University(巴黎天文台 LIRA 实验室,法国国家科学研究中心,PSL 大学,索邦大学,巴黎西岱大学,CY 塞尔吉巴黎大学)
Modelling $δ$ Scuti pulsations: A new grid of p, g, and f modes across pre-main-sequence to post-main-sequence evolution
Centre for Astrophysics, University of Southern Queensland(南昆士兰大学天体物理中心);Sydney Institute for Astronomy, School of Physics, University of Sydney(悉尼大学物理学院悉尼天文研究所)
经典造父变星(DCEP)是河外距离尺度最重要的主要指标,但它们本身也是重要的天体,使我们能够限制中等质量恒星的物理和脉动理论。我们已经调查了奇特的DCEP HD 344787,这是已知的表现出最快的正周期变化之间的DCEP随着猝灭振幅的光变化。我们已经使用了高分辨率的光谱与HARPS-N@TNG HD 344787和更著名的北极星DCEP,推断其详细的化学丰度。本文还报道了TESS卫星对HD 344787进行新的时间序列测光分析的结果。HD 344787脉动的双模性质通过TESS光变曲线的分析得到了证实,尽管其振幅非常小,只有几十毫等。这表明HD 344787即将抑制脉动。对HARPS-N@TNG光谱的分析揭示了几乎太阳的丰度,并且没有碳和氧的耗尽。因此,这颗恒星似乎没有经历过第一次挖掘。Polaris也得到了类似的结果。北极星和HD 344787都被证实是最有可能在他们的第一次穿越不稳定带(IS)。这两颗恒星可能位于IS的相对边界,金属丰度Z=0.008。与其他也被认为是第一次交叉的DCEP进行比较,使我们能够推测,我们在赫兹-罗素图中看到的差异可能是由于DCEP祖先在主层序阶段的性质差异。
Pulsations of rapidly rotating stars: I. The ACOR numerical code
非常高精度的地震空间任务,如CoRoT和开普勒提供了测试恒星内部传输过程建模的手段。对于某些恒星,例如类太阳恒星和红巨星,测量到旋转分裂。然而,为了充分利用这些分裂并约束旋转轮廓,需要能够准确地计算它们。对于其他一些恒星,例如$δ$ Scuti和Be星,观测到的脉动光谱被旋转改变到这样的程度,以至于对旋转效应的微扰处理不再有效。我们在这里提出了一个新的二维非微扰代码,称为ACOR(\textit{Adiabatic Code of Oscillation including Rotation}),它使我们能够计算绝热非径向脉动的旋转恒星,而不作任何假设的球形的恒星,流体性质(即斜压)或旋转配置文件。二维非微扰计算充分考虑了恒星的离心畸变,并包括科里奥利加速度的全部影响。数值方法的基础上的频谱方法的角度部分的模式,和四阶有限差分法的径向部分。我们测试和评估的准确性的计算进行比较,与那些来自TOP(\textit{Two-dimensional Oscillation Program})相同的多方模型。我们通过避免交叉现象说明了快速旋转对恒星脉动的影响。与简单模型的TOP比较表明,该代码是稳定的,并且在近临界旋转速率下给出了准确的结果。