Astronomers have discovered that a pulsar’s releases of enormous amounts of matter in short periods of time, in something that resembles “cosmic cannonballs”, are responsible for the alternation in brightness modes characteristic of this type of star.
The discovery was disclosed this Wednesday (30), in a scientific article published in the journal Astronomy & Astrophysics.
The observation campaign involved the use of 12 telescopes, both on the ground and in space, including structures from the European Southern Observatory (ESO). The scientists’ idea was to investigate the strange behavior of the pulsar J1023, located 4500 light years from planet Earth.
“We have just observed extraordinary cosmic events, where huge amounts of matter, similar to cosmic cannonballs, are launched into space in a very short space of time (on the order of tens of seconds), by a small and dense celestial object that rotates at extremely high speeds”, explained Maria Cristina Baglio, a researcher at the University of New York in Abu Dhabi, affiliated with the Italian National Institute of Astrophysics (INAF), and co-author of the scientific article.
What are pulsars?
Pulsars are neutron stars — that is, dead stars — that are magnetic and rapidly rotating.
“A neutron star is a stellar corpse. In its trajectory, it creates a very dense “lump”, it collapses and the protons absorb the electrons, turning into neutrons”, explains astronomer Augusto Damineli, professor at the Institute of Astronomy, Geophysics and Atmospheric Sciences at the University of São Paulo (USP).
They emit a beam of electromagnetic radiation that, as it rotates, sweeps the cosmos like a lighthouse. When it intersects Earth’s line of sight, the pulsar can be identified by scientists, in an effect that makes the star appear to be pulsing in brightness.
“There are many more pulsars than we can see, because each place in the Universe receives the light of a certain pulsar”, highlights Damineli.
VIDEO – Artistic animation shows the pulsar PSR J1023+0038
According to the article, the studied pulsar orbits close to another star, from which it actively extracts matter. This matter builds up in the disk around the neutron star, slowly falling towards it.
In this process of accumulating matter, the pulsar alternates between two modes: “high”, when it emits bright x-rays, ultraviolet and visible light, and “low”, when it becomes weaker for these frequencies, but emits more in the lower frequencies. radio waves.
“We found that the mode shift results from an intricate interaction between the pulsar’s wind — a stream of high-energy particles moving away from the pulsar — and matter flowing toward the pulsar,” says Coti Zelati, also an INAF affiliate. and staff member who signs the survey.
When the pulsar is in low mode, matter flowing towards it is expelled in a narrow jet perpendicular to the disk. Gradually, such matter accumulates near the dead star and is hit by the pulsar’s wind, which heats it up.
In a few seconds, the system switches to high mode, where intense brightness in x-rays, ultraviolet and visible light occurs.
The mode switch occurs again within seconds, as bubbles of hot matter are removed by pulsing through the jet. With less hot matter, the system glows less, switching to low mode in a constant process.
The researchers point out that although the discovery is important for understanding how J1023 works, there is still much to discover about the system.
Source: CNN Brasil
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