Pulsar J1023. Astronomers have discovered its secret

A pulsar is a dead, highly magnetized star that rotates rapidly on its axis. Their distinguishing feature is the beam of electromagnetic radiation emitted from them. As the pulsar spins, its beam spreads through space like a giant beacon, making it appear to the observer that the star is changing in brightness. However, not all stars behave in the same way – one example is PSR J1023+0038, J1023 for short, whose unusual behavior has baffled astronomers.

J1023 is located about 4,500 light-years from Earth in the constellation Sextant. The object is not alone, but is orbiting another star, which is actively drawing gas and dust from it, and material has been accumulating in a disk around the pulsar, slowly falling toward its surface.

Since J1023 started “stealing”, its behavior has completely changed. The beam of light practically disappeared, and the pulsar began to switch between two modes of operation: at “high” it emits X-rays, ultraviolet and visible light, while at “low” it emits more radio waves. Each stage lasts from a few seconds to several minutes, and the transition from one stage to the next takes seconds.

This endless shift baffled astronomers, who decided to investigate the object’s unusual behaviour. 12 instruments were pointed at J1023, including the European Southern Observatory’s (ESO) VLT telescopes (A very large telescope, the Very Large Telescope), the NTT (New Technology Telescope), which detected visible light and infrared radiation, and the ALMA radio interferometer. Over two nights in June 2021, the system was observed to have made more than 280 switches between high and low modes.

– We found that the mode switch is due to the relationship between the pulsar wind, the flow of high-energy particles emitted by the pulsar, and the material falling towards the dead star. – explained Francesco Coti-Zelati of the University of Barcelona, ​​co-author of the study.

In the lowered position, the material is ejected in a narrow beam perpendicular to the disc. As it gradually builds up closer and closer to the star, where it is exposed to the stellar wind, it heats up and glows – so the system rises. After some time, specks of hot matter enter the beam and are removed from the disc. When there is less, the system lights up less brightly, and switches to low mode.

“We have witnessed extraordinary cosmic events in which huge amounts of matter, similar to cosmic cannonballs, were shot into space in just a few tens of seconds,” said Maria Cristina Baglio of New York University Abu Dhabi, lead author of the study published in the scientific journal Nature. “. Astronomy and astronomy. Astrophysics”.

Although scientists have learned the secret of J1023’s behavior, they still have a lot to learn from studying this unique system. ESO hopes. The Extremely Large Telescope (ELT) being built in Chile will allow us to better understand the mechanisms of switching modes of a pulsar and how the distribution and amount of incoming matter affects its activity.