Approximately 10% of massive OBA main-sequence (MS) and pre-MS stars harbour strong, large-scale magnetic fields. At the same time there is a dearth of magnetic stars in close binaries. A process generating strong magnetic fields only in some stars must be responsible with the merging of pre-MS and MS stars being suggested as one such channel. Stars emerging from the coalescence of two MS stars are rejuvenated, appearing younger than they are. They can therefore be identified by comparison with reference clocks. Here we predict the rejuvenation of MS merger products over a wide range of masses and binary configurations calibrated to smoothed-particle-hydrodynamical merger models. We find that the rejuvenation is of the order of the nuclear timescale and is strongest in the lowest-mass mergers and the most evolved binary progenitors with the largest mass ratios. These predictions allow us to put constraints on the binary progenitors of merger products. We show that the magnetic stars HR 2949 and $τ$ Sco are younger than the potential binary companion HR 2948 and the Upper-Sco association, respectively, making them promising merger candidates. We find that the age discrepancies and the potential binary progenitors of both are consistent with them being rejuvenated merger products, implying that their magnetic fields may originate from this channel. Searching for age discrepancies in magnetic stars is therefore a powerful way to explore which fraction of magnetic stars may have obtained their strong magnetic field in MS mergers and to improve our understanding of magnetism in massive stars and their remnants.
On the origin of carbon- and oxygen-rich hot subdwarfs: an sdB merger scenario
Institute for Frontier in Astronomy and Astrophysics, Beijing Normal University（前沿天文学与天体物理研究所，北京师范大学）；School of Physics and Astronomy, Beijing Normal University（物理与天文学院，北京师范大学）
Evolution of Massive Main-sequence Stars in Rapid Population Synthesis. I. Framework and Implementation
Monash University（莫纳什大学）；OzGrav: The ARC Centre of Excellence for Gravitational Wave Discovery（引力波发现ARC卓越中心）；Astrophysical Big Bang Laboratory (ABBL), Pioneering Research Institute (PRI), RIKEN（理化学研究所先导研究院天体物理大爆炸实验室）
Reproducing the observed abundances in RCB and HdC stars with post-double degenerate merger models - constraints on merger and post-merger simulations and physics processes
Distinguishing the Origin of Eccentric Black Hole Mergers with Gravitational-wave Spin Measurements
Max Planck Institute for Astrophysics（马克斯·普朗克天体物理研究所）；Dipartimento di Fisica “G. Occhialini”, Università degli Studi di Milano-Bicocca（米兰比可卡大学 G. Occhialini 物理系）；INFN, Sezione di Milano-Bicocca（意大利国家核物理学会米兰比可卡分部）；Department of Applied Mathematics and Theoretical Physics, Cambridge（剑桥大学应用数学与理论物理系）；Kavli Institute for Cosmology Cambridge（剑桥卡弗里宇宙学研究所）；Shanghai Astronomical Observatory（上海天文台）；Niels Bohr International Academy, The Niels Bohr Institute（尼尔斯·玻尔国际学院，尼尔斯·玻尔研究所）
Violent mergers revisited: The origin of the fastest stars in the Galaxy
Max-Planck-Institut für Astrophysik（马克斯·普朗克天体物理学研究所）；University of California, Berkeley（加州大学伯克利分校）；Universität Potsdam（波茨坦大学）；Trinity College Dublin（都柏林圣三一学院）；Lawrence Livermore National Laboratory（劳伦斯利弗莫尔国家实验室）；Center for Astrophysics | Harvard & Smithsonian（哈佛与史密森尼天体物理中心）；Queen’s University Belfast（贝尔法斯特女王大学）；Zentrum für Astronomie der Universität Heidelberg（海德堡大学天文中心）；Heidelberger Institut für Theoretische Studien（海德堡理论研究所）
