Weng, Shan ShanShan ShanWengQian, LeiLeiQianWang, Bo JunBo JunWangTorres, D. F.D. F.TorresPAPITTO, ALESSANDROALESSANDROPAPITTOJiang, PengPengJiangXu, RenxinRenxinXuLi, JianJianLiYan, Jing ZhiJing ZhiYanLiu, Qing ZhongQing ZhongLiuGe, Ming YuMing YuGeYuan, Qi RongQi RongYuan2025-02-122025-02-1220222397-3366http://hdl.handle.net/20.500.12386/35921LS I +61° 303 is one of the rare gamma-ray binaries1 that emit most of their luminosity in photons with energies beyond 100 MeV (ref. 2). It is well characterized—the ~26.5 day orbital period is clearly detected at many wavelengths2–4—and other aspects of its multifrequency behaviour make it the most interesting example of its class. The morphology of high-resolution radio images changes with orbital phase, displaying a cometary tail pointing away from the high-mass star component5 and LS I +61° 303 also shows superorbital variability3,6–9. A couple of energetic (~1037 erg s−1), short, magnetar-like bursts have been plausibly ascribed to it10–13. Although the phenomenology of LS I +61° 303 has been the subject of theoretical scrutiny for decades, there has been a lack of certainty regarding the nature of the compact object in the binary that has hampered our understanding of the source. Here, using observations with the Five-hundred-meter Aperture Spherical radio Telescope, we report the existence of transient radio pulsations from the direction of LS I +61° 303 with a period P = 269.15508 ± 0.00016 ms at a significance of >20σ. These pulsations strongly argue for the existence of a rotating neutron star within LS I +61° 303.ELETTRONICOenArticle10.1038/s41550-022-01630-12-s2.0-85126341930https://api.elsevier.com/content/abstract/scopus_id/85126341930https://arxiv.org/pdf/2203.09423https://www.nature.com/articles/s41550-022-01630-1FIS/05 - ASTRONOMIA E ASTROFISICA