Magnetars are young neutron stars with extreme magnetic fields (B > 10^{14}-10^{15}G). How these fields relate to the properties of their progenitor stars is not yet clearly established. However, from the few objects associated with young clusters it has been possible to estimate the initial masses of the progenitors, with results indicating that a very massive progenitor star (M_prog >40Msun) is required to produce a magnetar. Here we present adaptive-optics assisted Keck/NIRC2 imaging and Keck/NIRSPEC spectroscopy of the cluster associated with the magnetar SGR 1900+14, and report that the initial progenitor star mass of the magnetar was a factor of two lower than this limit, M_prog=17 \pm 2 Msun. Our result presents a strong challenge to the concept that magnetars can only result from very massive progenitors. Instead, we favour a mechanism which is dependent on more than just initial stellar mass for the production of these extreme magnetic fields, such as the "fossil-field" model or a process involving close binary evolution.
SGR 1935+2154's Quiet Local Environment: Clues for Its Progenitor
School of Astronomy and Space Science, Nanjing University（南京大学天文与空间科学学院）；Key Laboratory of Modern Astronomy and Astrophysics, Nanjing University, Ministry of Education（南京大学现代天文与天体物理教育部重点实验室）；South-Western Institute for Astronomy Research, Yunnan University（云南大学西南天文研究所）
EP250108a/SN2025kg: A Magnetar-powered Gamma-Ray Burst Supernova Originating from a Close Helium-star Binary via Isolated Binary Evolution
The Hong Kong Institute for Astronomy and Astrophysics, The University of Hong Kong（香港大学天文及天体物理研究所）；Department of Physics, The University of Hong Kong（香港大学物理系）；School of Physics and Astronomy, Monash University（蒙纳士大学物理与天文学院）；OzGrav: The ARC Centre of Excellence for Gravitational Wave Discovery（ARC引力波发现卓越中心）；School of Astronomy and Space Science, Nanjing University（南京大学天文与空间科学学院）；Departments of Astronomy and Theoretical Astrophysics Center, UC Berkeley（加州大学伯克利分校天文系和理论天体物理中心）；Nevada Center for Astrophysics and Department of Physics and Astronomy, University of Nevada, Las Vegas（内华达大学拉斯维加斯分校天体物理中心和物理与天文系）
A statistical study of super-luminous supernovae in the magnetar engine model and implications for their connection with gamma-ray bursts and hypernovae
Novae breves from magnetar giant flares: Potential probes of neutron star crusts
Peking University（北京大学）；Kavli Institute for Astronomy and Astrophysics, Peking University（北京大学科维理天文与天体物理研究所）；Guangxi Key Laboratory for Relativistic Astrophysics, School of Physical Science and Technology, Guangxi University（广西大学物理科学与技术学院相对论天体物理重点实验室）；National Astronomical Observatories, Chinese Academy of Sciences（中国科学院国家天文台）
Magnetar counterparts, kinematics and birth sites with HST and JWST
European Space Agency (ESA), European Space Research and Technology Centre (ESTEC)（欧洲航天局（ESA）欧洲空间研究与技术中心（ESTEC））；Department of Astrophysics/IMAPP, Radboud University（拉德堡德大学天体物理学系/IMAPP）；Department of Physics, University of Warwick（华威大学物理系）；European Space Agency (ESA), European Space Astronomy Centre (ESAC)（欧洲航天局（ESA）欧洲空间天文中心（ESAC））；Space Telescope Science Institute（太空望远镜科学研究所）；Istituto Nazionale di Astrofisica (INAF) – Osservatorio Astronomico di Palermo（意大利国家天体物理研究所（INAF）- 巴勒莫天文台）；Department of Physics, The George Washington University（乔治华盛顿大学物理系）；GWU/Astronomy, Physics and Statistics Institute of Sciences (APSIS)（乔治华盛顿大学/天体物理学、物理学和统计学科学研究所（APSIS））；School of Physics and Astronomy, University（物理与天文学学院，大学）
Ejector and propeller spin-down: How might a superluminous supernova millisecond magnetar become the 6.67 hr pulsar in RCW103
超新星遗迹RCW 103中的X射线源1 E 161348-5055最近表现出磁星的典型X射线活动，即磁场> 10 ^14 - 10 ^15 G的中子星。然而，1 E 161348-5055的观测周期为6.67小时，而磁星的自旋周期为秒。在这里，我们描述了一个简单的模型，它可以解释1 E 161348-5055的自旋演化，以及其他磁星，从一个初始的毫秒，将需要发电机产生的磁场强度磁场。我们认为，1 E 161348-5055与其他磁星的关键区别在于其残留盘的总质量较小。这个圆盘导致1 E 161348-5055在其生命中经历了喷射器和螺旋桨阶段，在此期间，强大的扭矩导致其自旋周期迅速增加。通过匹配观测到的自旋周期和1-3 kyr的年龄，我们发现1 E 161348-5055在所有已知的磁星中具有（略）最高的磁场，B~ 5 × 10^15 G，其盘的质量约为10^24 g，与小行星谷神星相当。
