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Pulsar J1023. Astronomers have discovered its secret

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Astronomers have solved the mystery of a pulsar that changes its brightness in rapid cycles. The object, 4,500 light-years away from us, was quite a puzzle for scientists because no similar body behaved in such a way. However, this is not the end of research on this mysterious system.

A pulsar is a dead, highly magnetized star that spins rapidly around its axis. Its characteristic feature is the beam of electromagnetic radiation it emits. As the pulsar rotates, the beam sweeps around cosmos like a giant lighthouse, which may make it appear to the observer that the star is changing its brightness. However, not all stars behave the same – an example is PSR J1023+0038, J1023 for short, whose unusual behavior has puzzled astronomers.

Complete behavior change

J1023 is located about 4,500 light-years from Earth in the constellation Sextant. The object is not alone, but orbits another star from which it is actively extracting gas and dust – material accumulated in the disk around the pulsar, slowly falling towards its surface.

Since J1023 started “stealing”, his behavior has completely changed. The light beam virtually disappeared, and the pulsar began to switch between two operating modes: in “high” it emits X-ray, ultraviolet and visible radiation, while in “low” it emits more radio waves. Each phase lasts from a few seconds to a few minutes, and the transition from one to the other takes seconds.

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This endless switching surprised astronomers, who decided to look into the object’s unusual behavior. Twelve measuring devices were aimed at J1023, including the European Southern Observatory’s (ESO) VLT telescopes (Very Large Telescope, Very Large Telescope) and NTT (New Technology Telescope), which detected visible and infrared light, and the ALMA radio interferometer. Over two nights in June 2021, the system was observed to make over 280 switches between high and low modes.

Pulsar PSR J1023+0038 “stealing” material from a neighboring starESO/M. Kornmesser

A complicated process

We found that the mode switching results from a relationship between the pulsar wind, the flow of high-energy particles blowing away from the pulsar, and material falling toward the dead star.Translated by Francesco Coti Zelati from the University of Barcelona, ​​co-author of the study.

In low mode, material is ejected in a narrow beam perpendicular to the disk. It gradually gathers closer to the star, where it is exposed to the stellar wind, heating up and glowing brightly – thus the system goes high. After some time, spots of hot material enter the beam and are removed from the disk. When there is less light, the system shines less brightly, switching to low mode.

– We witnessed extraordinary cosmic events in which huge amounts of matter, similar to cosmic cannonballs, were shot into space in just a few dozen seconds – said Maria Cristina Baglio from New York University in Abu Dhabi, lead author of the article published in “Astronomy & Astrophysics”.

Although scientists have learned the mystery behind J1023’s behavior, they can still learn a lot from studying this unique system. ESO has hope. that the Extremely Large Telescope (ELT), being built in Chile, will allow us to better understand the mechanisms of pulsar mode switching and how the distribution and amount of incoming matter affect its activity.

Main photo source: ESO/M. Kornmesser



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