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Earth is not the only world adorned with the brilliant atmospheric phenomenon of dawn. In fact, in a solar system aurora contest, the big winner would be Jupiter. The so-called king of the planets is crowned with the most powerful auroras in the solar system, constantly circling both of his poles.
Because they only glow in wavelengths that are not visible, we cannot see them with the naked eye, so it was only 40 years ago that they were discovered. Since then, scientists have wondered how these auroras produce periodic bursts of X-radiation.
Now they think they’ve solved the problem. Using simultaneous observations from the Jupiter Juno probe and the XMM-Newton X-ray space observatory, a team led by planetologist Zhonghua Yao of the Chinese Academy of Sciences in China has linked the X-ray bursts to vibrations in the magnetic field lines of the gas giant.
These vibrations generate waves in the plasma that propagate along magnetic field lines, periodically causing heavy ion rain and colliding with Jupiter’s atmosphere, releasing energy in the form of x-rays.
“We have seen Jupiter produce auroras X for four decades, but we didn’t know how it happened. We only knew that they were produced when ions crashed into the planet’s atmosphere,” explained astrophysicist William Dunn of University College London in the United Kingdom. .
“Now we know that these ions are carried by plasma waves – an explanation that has not been offered before, although a similar process produces Earth’s own aurora. So it could be a universal phenomenon. , present in many different environments in space. “
Here on Earth, the auroras are generated by particles coming from the Sun. They collide with the Earth’s magnetic field, which sends charged particles like protons and hissing electrons along magnetic field lines to the poles, where they rain down on Earth’s upper atmosphere and collide with atmospheric molecules. The resulting ionization of these molecules generates breathtaking dancing lights.
On Jupiter, there are some differences. Auroras are constant and permanent, as previously stated; this is because the particles are not solar, but from the Jovian moon Io, the most volcanic world in the solar system. It constantly spits out sulfur dioxide, which is immediately extracted via a complex gravitational interaction with the planet, ionizing and forming a plasma torus around Jupiter.
And then there are the X-ray pulses. To understand how they were generated, the research team studied the planet, using simultaneous observations from Juno and XMM-Newton, taken on July 16 and 17, 2017. , for a total of 26 hours. During this time, Jupiter was emitting a burst of X-rays about every 27 minutes.
Based on these observations, the team linked the Juno observations of plasma with the XMM-Newton observations of x-ray auroral bursts; with computer modeling, they determined how the two phenomena might be related.
The team concluded that compressions in Jupiter’s magnetic field create waves of oxygen and sulfur ions that spiral along magnetic field lines toward Jupiter’s poles, where they rain, collide with the atmosphere and generate X-ray bursts.
These waves are called ionic cyclotron electromagnetic waves (or EMICs), and they have also been linked to flickering auroras here on Earth.
It is not known, at this point, what causes the compressions in Jupiter’s magnetic field. It could be the influence of the solar wind, the circulation of heavy materials within the Jovian magnetosphere, or surface waves on the magnetopause, the outer border between the magnetosphere and the surrounding plasma.
Regardless of how the compressions are generated, the fact that the same mechanism – EMIC waves – has been linked to auroral emissions on two very different worlds suggests that this could be quite common in the solar system, as well as in the galaxy. beyond.
“Now that we have identified this fundamental process, there is a plethora of possibilities to study it next,” said Yao.
“Similar processes are probably occurring around Saturn, Uranus, Neptune, and possibly exoplanets as well, with different types of charged particles ‘surfing’ the waves.”
The results show that EMIC waves could play an important, so far unnoticed, role in the ionic dynamics of Jupiter’s atmosphere, and could help us better understand plasma processes across the galaxy.
The research was published in Scientists progress.
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