AI 中文总结
本研究通过两种策略选取七颗慢旋转化学特殊A型星，经高分辨率光谱偏振观测，发现5200埃凹陷加TESS旋转调制的选星方法可高效定位磁性A型星，慢旋转加化学特殊性无法可靠识别这类磁场。
AI 中文摘要
一小部分A型星拥有强的化石磁场，对它们的识别依赖化学特殊性、慢旋转、旋转调制等间接指标，但这些指标也存在于非磁性星中，评估其可靠性对未来巡天至关重要。我们通过两种互补策略选取七颗慢旋转、化学特殊的A型星，对其进行磁学表征：三颗是通过丰度分析结合潜在的本征慢旋转选取，四颗是通过5200埃谱线凹陷结合TESS测光中的旋转调制选取。我们获取高分辨率光谱偏振数据，应用最小二乘退卷积法，对探测到的星测量纵向磁场强度；对未探测到的星，推导极向磁场强度的上限，并评估Zahn和Spruit的临界磁场。我们在通过谱线凹陷和测光标准选取的全部四颗星中探测到磁场，纵向磁场强度约为145-2900高斯；而通过丰度和慢旋转选取的三颗星均未显示塞曼信号。两颗未探测星的组合上限低于或接近磁场荒漠边界，但仅有一颗也低于刚性旋转所需的临界磁场，这些未探测星最可能被解释为Am星。在探测到的星中，HD 63843作为一颗磁变δ Scuti脉动星脱颖而出，有望用于磁 asteroseismology（磁 asteroseismology 为保留的专业术语）。综上，仅慢旋转结合化学特殊性无法可靠追踪大尺度磁场，而加入5200埃谱线凹陷和空间测光中的稳定旋转调制，似乎能高效选取磁性A型星，为未来光谱偏振巡天提供实用指南。
英文摘要
A small fraction of A-type stars host strong fossil magnetic fields. Identifying them relies on indirect indicators such as chemical peculiarities, slow rotation, and rotational modulation, which are also shared by non-magnetic stars. Assessing their reliability is essential for future surveys. We magnetically characterise seven slowly rotating, chemically peculiar A-type stars selected through two complementary strategies. Three were selected from abundance analysis combined with potential intrinsically slow rotation, and four from a spectral depression at 5200 Angstrom combined with rotational modulation in TESS photometry. We obtained high-resolution spectropolarimetry, applied least squares deconvolution, and measured longitudinal field strengths for detections. For non-detections, we derived upper limits on polar field strength and evaluated the critical fields of Zahn and Spruit. We detect magnetic fields in all four stars selected via the spectral depression and photometric criterion, with longitudinal field strengths of approximately 145-2900 G, while none of the three stars selected via abundance and slow rotation shows a Zeeman signature. Combined upper limits for two non-detections lie below or near the magnetic desert boundary, but only one is also below the critical fields required for rigid rotation. The non-detections are most naturally interpreted as Am stars. Among the detections, HD 63843 stands out as a magnetic $δ$ Scuti pulsator, promising for magneto-asteroseismology. In conclusion, slow rotation combined with chemical peculiarity alone does not reliably trace large scale magnetic fields, whereas adding the 5200 Angstrom depression and stable rotational modulation in space photometry appears to select magnetic A-type stars with high efficiency, providing a practical guideline for future spectropolarimetric surveys.
Comments13 pages, 6 figures, 7 tables (including appendices)
DOI：10.1051/0004-6361/202661173
