Optical and ultraviolet pulsed emission from an accreting millisecond pulsar

Millisecond spinning, low-magnetic-field neutron stars are believed to attain their fast rotation in a 0.1–1-Gyr-long phase during which they accrete matter endowed with angular momentum from low-mass companion star1. Despite extensive searches, coherent periodicities originating accreting star magnetospheres have been detected only at X-ray energies2 and ~10% of the currently known systems3. Here we report detection optical ultraviolet pulsations period transient binary system SAX J1808.4?3658, an accretion outburst that occurred August 20194. At time observations, pulsar was surrounded by disk, displayed its luminosity consistent magnetically funnelled onto star. Current models fail account for both pulsations; these instead more likely be driven synchro-curvature radiation5,6 magnetosphere or just outside it. This interpretation would imply particle acceleration can take place even when mass is going on, opens up new perspectives study optical/ultraviolet fast-spinning systems. Outbursts pulsars encode much information on Measuring as well constrain and, indeed, point taking accretion.