Jupiter Finally, spitting out X-rays at high-energy wavelengths was observed.
Emanations from the giant planet’s permanent auroras, detected by NASA’s X-ray Space Telescope nostaremissions are the most energetic light seen coming from any planet in the solar system (except Earth).
This discovery could shed light on the most powerful aurora borealis in the solar system, and solve an age-old mystery: why the European Space Agency and NASA share Ulysses The spacecraft did not detect any Jovian x-rays during its nearly three decades of operation between 1990 and 2009.
The formation of the aurora borealis of Jupiter is a very remarkable phenomenon. At both poles, the planet is surrounded by perpetual auroras — invisible to our eyes, but glowing brilliantly at ultraviolet wavelengths. These regions have also been observed emitting low-energy or “soft” X-rays by the Chandra and XMM-Newton X-ray observatories.
Scientists believe that there must also be high energy, or ‘hard’ x-rays, beyond what these devices can detect. So they used Neustar to search for it.
“It’s very difficult for planets to generate x-rays in the range that Neustar detects,” Astrophysicist Kaia Morey said: from Columbia University.
“But Jupiter has an enormous magnetic field, and it’s spinning really fast. These two properties mean that the planet’s magnetosphere acts like a giant particle accelerator, and that’s what makes these high-energy emissions possible.”
Jupiter’s aurora borealis are similar to and different from the aurora borealis on Earth, as they are generated by particles blowing from the sun. They collide with Earth’s magnetic field, which sends charged particles such as protons and electrons that oscillate along magnetic field lines toward the poles, where they rain down on Earth’s upper atmosphere and collide with atmospheric particles. The resulting ionization of these particles generates amazing dancing lights.
On Jupiter, the basic mechanism is similar, but there are some differences. The aurora borealis is constant and permanent, as noted earlier; That’s because the particles are not solar, but from Jovian’s moon Io, the most volcanic world in the solar system.
It constantly emits sulfur dioxide, which is instantly stripped away by a complex gravitational interaction with the planet, ionizing and forming a plasma hoop around the gas giant. Particles from this hoop are sent buzzing along magnetic field lines to the poles, etc.
Emission detected by NuSTAR. (NASA/JPL-Caltech)
This process generates soft X-rays, as was discovered earlier. Now, a harsh X-ray has also been found. It wasn’t an easy find, as the high-energy X-rays are quite faint, but the researchers said that doesn’t explain why Ulysses couldn’t detect them. They find that the answer lies in the way the difficult X-rays are generated.
When electrons accelerate along Jupiter’s magnetic field lines, they end up entering the planet’s atmosphere at high speed. When these electrons enter near the atomic nuclei and their electric fields, these electrons are suddenly deflected and slowed down. However, their kinetic energy has to go somewhere, according to the law of conservation of energy, so that it is converted into X radiation.
This is called bremsstrahlung, or radiation braking. Soft X-rays are generated via a different mechanism called charge exchange, in which electrons are transferred into ions, which excitation generates a glow.
These mechanisms produce a different optical profile, the researchers said. At higher energies, bremsstrahlung x-rays have to be fainter at higher energies, which explains why Ulysses never finds them.
The team modeled data including the bremsstrahlung mechanism, and not only matched the NuSTAR observations, but showed that the emissions are outside the sensitivity range of the Ulysses. Good so far, but we are just starting to investigate this phenomenon.
For example, while NuSTAR was able to detect hard X-rays in the general region of the Jovian aurora, it was not able to determine an exact emission point.
“The discovery of these emissions does not close the case; it opens a new chapter,” Astronomer William Dunn said, from University College London in the United Kingdom.
“We still have a lot of questions about these emissions and their sources. We know that rotating magnetic fields can accelerate particles, but we don’t fully understand how they reach such high speeds on Jupiter. What are the basic processes that naturally produce such energetic particles?” “
Future X-ray studies of Jupiter’s aurora borealis could help shed more light on the physics in play.
The search was published in natural astronomy.
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