2023-08-30 15:14:43
A team of astronomers and astronomers has discovered the origin of the strange behavior of a pulsate. Thanks to an international observation campaign, the team has detected that these sudden changes are due to sudden ejections of matter by the pulsar in very short periods.
“We have witnessed extraordinary cosmic events where enormous amounts of matter, similar to cosmic cannonballs, are launched into space in a very short time span, tens of seconds, from a small, dense celestial object rotating at incredibly fast speeds. tall”, declare Maria Cristina Baglioresearcher at the University of New York Abu Dhabi, affiliated with the Italian National Institute of Astrophysics (INAF) and lead author of the article published today in Astronomy & Astrophysics.
We observe extraordinary cosmic events where enormous amounts of matter, similar to cosmic cannonballs, are launched into space in a very short time.
Maria Cristina Baglio (NYU Abu Dhabi)
A pulsar is a fast-rotating, magnetic, dead star that emits a beam of electromagnetic radiation into space. As it rotates, this beam crosses the cosmos (just like a lighthouse beam) and is detected by the astronomical community when it crosses the line of sight we see from Earth. This makes the star’s brightness appear to pulsate when viewed from our planet.
The authors have focused on PSR J1023+0038, o J1023 for short, a special type of pulsar with strange behavior. Located about 4,500 light-years away, on the sextant constellationclosely orbits another star.
For the past decade, the pulsar has been actively subtracting material from this companion. This material has been accumulating in a disk around the pulsar and is slowly falling towards it.
Since this process of accumulation of matter began, the beam of light practically disappeared and the pulsar began to intermittently switch between two modes.
The pulsar emits X-rays, UV and visible light in the “high” mode, while in the “low” mode, more radio waves
In the “high” mode, the pulsar emits 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. These changes have baffled the astronomical community until now.
Twelve ground and space telescopes
“Our unprecedented observing campaign, developed to understand the behavior of this pulsar, involved a dozen state-of-the-art ground and space telescopes,” says co-author Francesco Coti Zelatiresearcher at the Institute of Space Sciences (ICE-CSIC) and the Institute for Space Studies of Catalonia (IEEC).
The campaign included the European Southern Observatory’s (ESO) Very Large Telescope (VLT) and New Technology Telescope (NTT), which detected visible and near-infrared light, as well as the Atacama Large Millimeter/submillimeter Array (ALMA), from which ESO is partner. Over two nights in June 2021, they observed the system make more than 280 changes between its high and low modes.
“We have discovered that the mode change comes from an intricate interaction between the pulsar’s wind, a stream of high-energy particles moving away from it, and matter flowing into the pulsar,” says Coti Zelati, who is also affiliated with the INAF.
The mode change comes from an intricate interaction between the pulsar’s wind, a stream of high-energy particles moving away, and matter flowing toward it.
Francesco Coti Zelati (ICE-CSIC/IEEC)
In low mode, matter flowing into the pulsar is ejected in the form of tight squirt, perpendicular to the disk. Little by little, this matter accumulates closer and closer to the pulsar, and as this happens, it is buffeted by the winds blowing from the pulsating star, causing the matter to heat up.
That causes the system to go into high mode, glowing brightly in X-rays, ultraviolet, and visible light. Finally, these masses of hot matter are removed by the pulsar through the jet. With less hot matter on the disk, the system glows less brightly, returning to low mode.
While this discovery has unraveled the mystery of J1023’s strange behavior, the astronomical community still has much to learn from studying this unique system, and ESO telescopes will continue to help observe this peculiar pulsar. In particular, the Extremely Large Telescope (ELT) from ESO, currently under construction in Chile, will offer unprecedented insight into the switching mechanisms of J1023.
“The ELT will allow us to obtain key information on how the abundance, distribution, dynamics, and energy of the incoming matter around the pulsar are affected by mode-switching behavior,” he concludes. Sergio CampanaResearch Director of the INAF Brera Observatory and co-author of the study.
Reference:
M. C. Baglio et al. “Matter ejections behind the highs and lows of the transitional millisecond pulsar PSR J1023+0038”. Astronomy & Astrophysics2023.
Rights: Creative Commons.
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