European Southern Observatory Telescopes Help Solve Pulsar Puzzle

European Southern Observatory Telescopes Help Solve Pulsar Puzzle

ESOcast 266 Light: With a remarkable observational campaign that involved 12 telescopes both on the ground and in space, including three European Southern Observatory (ESO) facilities, astronomers have uncovered the strange behavior of a pulsar, a super-fast-spinning dead star. This video summarizes the discovery.

A pulsar is a fast-rotating, magnetic, dead star that emits a beam of electromagnetic radiation into space. As it rotates, this beam sweeps across the cosmos—much like a lighthouse beam scanning its surroundings—and is detected by astronomers as it intersects the line of sight to Earth. This makes the star appear to pulse in brightness as seen from our planet.

PSR J1023+0038, or J1023 for short, is a special type of pulsar with a bizarre behavior. Located about 4,500 light-years away in the Sextans constellation, it closely orbits another star. Over the past decade, the pulsar has been actively pulling matter off this companion, which accumulates in a disc around the pulsar and slowly falls towards it. 

Since this process of accumulating matter began, the sweeping beam virtually vanished and the pulsar started incessantly switching between two modes. In the ‘high’ mode, the pulsar gives off bright X-rays, ultraviolet and visible light, while in the ‘low’ mode it is dimmer at these frequencies and emits more radio waves. The pulsar can stay in each mode for several seconds or minutes, and then switch to the other mode in just a few seconds. This switching has thus far puzzled astronomers.  

In the low mode, matter flowing towards the pulsar is expelled in a narrow jet perpendicular to the disc. Gradually, this matter accumulates closer and closer to the pulsar and, as this happens, it is hit by the wind blowing from the pulsating star, causing the matter to heat up. The system is now in a high mode, glowing brightly in the X-ray, ultraviolet and visible light. Eventually, blobs of this hot matter are removed by the pulsar via the jet. With less hot matter in the disc, the system glows less brightly, switching back into the low mode.

Credits: ESO

Directed by: Angelos Tsaousis and Martin Wallner

Editing: Angelos Tsaousis

Web and technical support: Gurvan Bazin and Raquel Yumi Shida

Written by: Claudia Sciarma and Tom Howarth

Footage and photos:  ESO / M. Kornmesser, Angelos Tsaousis, UHD Team, C. Malin, Theofanis Matsopoulos

Scientific consultant: Paola Amico, Mariya Lyubenova

Duration: 1 minute, 27 seconds

Release Date: Aug. 30, 2023

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