Strong organized magnetic fields have been studied in the upper main sequence chemically peculiar stars for more than half a century. However, only recently have observational methods and numerical techniques become sufficiently mature to allow us to record and interpret high-resolution four Stokes parameter spectra, leading to the first assumption-free magnetic field models of these stars. Here we present a detailed magnetic Doppler imaging analysis of the spectropolarimetric observations of the prototypical magnetic Ap star alpha^2 CVn. The surface abundance distributions of Fe and Cr and a full vector map of the stellar magnetic field are reconstructed in a self-consistent inversion using our state-of-the-art magnetic Doppler imaging code Invers10. We succeeded in reproducing most of the details of the available spectropolarimetric observations of alpha^2 CVn with a magnetic map which combines a global dipolar-like field topology with localized spots of higher field intensity. We demonstrate that these small-scale magnetic structures are inevitably required to fit the linear polarization spectra; however, their presence cannot be inferred from the Stokes I and V observations alone. Our magnetic Doppler imaging analysis of alpha^2 CVn and previous results for 53 Cam support the view that the upper main sequence stars can harbour fairly complex surface magnetic fields which resemble oblique dipoles only at the largest spatial scales. Spectra in all four Stokes parameters are absolutely essential to unveil and meaningfully characterize this field complexity in Ap stars. We therefore suggest that understanding magnetism of stars in other parts of the H-R diagram is similarly incomplete without investigation of their linear polarization spectra.
Further Investigation on Chromospheric Activity Patterns of the RS Canum Venaticorum Star V711 Tauri
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（国际超新星中心云南省重点实验室）；School of Astronomy and Space Science, University of Chinese Academy of Sciences（中国科学院大学天文与空间科学学院）
Radio Properties of RS Canum Venaticorum Variables in VLASS and RACS
University of Alberta（阿尔伯塔大学）；Clemson University（克莱姆森大学）；University of Sydney（悉尼大学）；University of Wisconsin-Milwaukee（威斯康星大学密尔沃基分校）；Australian Telescope National Facility, CSIRO Astronomy and Space Science（澳大利亚望远镜国家设施，CSIRO天文学与空间科学）
Origin of the stellar Fe Kα line clarified with FUV and X-ray observations of a superflare on the RS Canum Venaticorum-type Star UX Arietis
Kyoto University（京都大学）；Chiba University（千叶大学）；Tokyo University of Science（东京理科大学）；RIKEN Center for Advanced Photonics (RAP)（理化学研究所先进光子学中心）；University of Colorado Boulder（科罗拉多大学博尔德分校）；NASA’s Goddard Space Flight Center（美国国家航空航天局戈达德太空飞行中心）；University of Maryland, Baltimore County（马里兰大学巴尔的摩县分校）；Institute of Space and Astronautical Science, Japan Aerospace Exploration Agency（日本宇宙航空研究开发机构宇宙科学研究所）；Tohoku University（东北大学）；The University of Tokyo（东京大学）
Fe Kα equivalent-width mapping with 3D radiative transfer calculation: A general model and application to the RS Canum Venaticorum-type stars with XRISM/Resolve
Kyoto University（京都大学）；Institute of Space and Astronautical Science (ISAS), Japan Aerospace Exploration Agency (JAXA)（日本宇宙航空研究开发机构空间科学研究所）；Laboratory for Atmospheric and Space Physics, University of Colorado Boulder（科罗拉多大学博尔德分校大气与空间物理实验室）；The University of Tokyo（东京大学）；RIKEN Cluster for Pioneering Research（理化学研究所前沿研究集群）
Evidence of Long-Lived Powerful Gyrosynchrotron Radio Emission in the Close Binary FF UMa
Yunnan University（云南大学）；Chalmers University of Technology（查尔姆斯理工大学）；Sun Yat-Sen University（中山大学）；Shanghai Astronomical Observatory, Chinese Academy of Sciences（中国科学院上海天文台）；Finnish Geospatial Research Institute (FGI), National Land Survey of Finland（芬兰国家土地测量局芬兰地理研究所）；Yunnan Observatories, Chinese Academy of Sciences（中国科学院云南天文台）
The evolutionary history of ultra-compact accreting binaries. I. Chemical abundances and formation channel of the eclipsing AM CVn system ZTF J225237.05-051917.4 from HST spectroscopy
Hamburg Observatory, University of Hamburg（汉堡天文台，汉堡大学）；European Southern Observatory（欧洲南方天文台）；Department of Physics and Astronomy, Texas Tech University（德克萨斯理工大学物理与天文学系）；Department of Physics, University of Warwick（华威大学物理系）；Institut für Theoretische Physik und Astrophysik, University of Kiel（基尔大学理论物理与天体物理研究所）；São Paulo State University (UNESP), School of Engineering and Sciences（圣保罗州立大学（UNESP）工程与科学学院）；The Observatories of the Carnegie Institution for Science（卡内基科学机构天文台）；Department of Physics, University of California, Santa Barbara（加州大学圣塔芭芭拉分校物理系）；Departamento de Física, Universidad Técnica Federico Santa María（费德里科·圣玛丽亚技术大学物理系）；Institute of Science and Technology Austria（奥地利科学技术研究所）；Anton Pannekoek Institute for Astronomy, University of Amsterdam（阿姆斯特丹大学安东·潘农克天文研究所）
