PSR J1023 is a special type of pulsar with strange behavior. It is located about 4,500 light-years from Earth in the constellation Sextant and orbits another star. Over a long period of time, the pulsar actively pulled matter from its companion, which accumulated in the disk around the pulsar and gradually merged with it.

Since this material build-up process began, the pulsar has begun to switch between the two modes. In “high” mode it emits X-rays, ultraviolet and visible radiation, while in “low” mode it is less bright and emits more radio waves at these frequencies. A pulsar can be in any mode for a few seconds or minutes and then switch. These keys surprised astronomers.

“Our work was aimed at understanding the behavior of this pulsar. We included more than ten ground-based and space-based telescopes,” says co-author Francesco Coti Zelati of the paper. Over two nights of the year, telescopes observed the system more than 280 switching between high and low modes.

“We discovered that the regime change occurs because of the complex interaction of the flow of high-energy particles transported from the pulsar with the matter moving towards the pulsar,” says Koti Zelati. In the low luminosity regime, matter moving towards the pulsar is ejected in a narrow stream perpendicular to the disk. Gradually, this matter approaches the pulsar, and as it gets closer, it comes under the influence of radiation from the pulsating star and also heats up.

The system is in high brightness mode and shines brightly in X-ray, ultraviolet and visible light. When the amount of heated matter in the disk decreases, the star returns to a low luminosity mode.