A scientific team led by UCL (University College London) has figured out how Jupiter emits a dazzling burst of X-rays every few minutes, solving a decades-old riddle.
The X-rays are part of Jupiter’s aurora, which are flashes of visible and invisible light caused by charged particles colliding with the planet’s atmosphere.
A comparable phenomena occurs on Earth, causing the northern lights, but Jupiter’s is far more powerful, releasing hundreds of gigawatts of energy, enough to briefly power all of human civilization.* In a new study published in Science Advances, researchers coupled close-up measurements of Jupiter’s environment by NASA’s Juno satellite, which is now orbiting the planet, with simultaneous X-ray studies of the planet.
X-ray flares were identified to be caused by periodic vibrations of Jupiter’s magnetic field lines, according to a research team led by UCL and the Chinese Academy of Sciences.
These vibrations cause plasma (ionized gas) waves to form, which send heavy ion particles “surfing” along magnetic field lines until they collide with the planet’s atmosphere, releasing energy in the form of X-rays.
Dr. Dr. Dr. Dr. Dr. Dr. Dr. Dr. Dr. Dr. Dr
“We have seen Jupiter emitting X-ray aurora for four decades, but we didn’t know how this happened,” William Dunn (UCL Mullard Space Science Laboratory) explained.
They were only discovered after ions collided with the planet’s atmosphere.
“Now we know that these ions are transported by plasma waves — a theory that has never been offered previously, despite the fact that a comparable process produces Earth’s aurora.”
X-ray auroras occur in Jupiter’s north and south poles, frequently with clockwork regularity; during this observation, Jupiter was emitting bursts of X-rays every 27 minutes.
The charged ion particles that reach the atmosphere come from huge volcanoes on Jupiter’s moon Io spewing gas into space.
Due to collisions in Jupiter’s near atmosphere, this gas becomes ionized (its atoms are stripped of their electrons), generating a donut of plasma that encircles the planet.
Astronomers have witnessed for the first time how Jupiter’s magnetic field is compressed, which warms particles and drives them down the magnetic field lines into Jupiter’s atmosphere, sparking the X-ray aurora.
The link was made by merging in-situ data from NASA’s Juno mission with X-ray observations from the European Space Agency’s XMM-Newton spacecraft.
Dr. Dunn, co-lead author, ESA/NASA/Yao/Dunn
“Now that we have found this fundamental process, there are a multitude of possibilities for where it could be investigated next,” Zhonghua Yao (Chinese Academy of Sciences, Beijing) said.
Several sorts of charged particles’surf the waves’ of Saturn, Uranus, Neptune, and perhaps exoplanets, according to co-author Professor Graziella Branduardi-Raymont (UCL Mullard Space Science Laboratory): “X-rays are normally created by incredibly powerful and destructive events such as black holes and neutron stars, so it seems unusual that simple pools
“We will never be able to visit black holes because they are beyond our ability to travel through space, yet Jupiter is right around the corner.”
Astronomers now have a fantastic opportunity to investigate an environment that produces X-rays up close, thanks to the entry of the Juno satellite into Jupiter’s orbit.” For the current study, researchers evaluated observations of Jupiter and its surrounding environment carried out continuously over a 26-hour period by the Juno and XMM-Newton satellites.
They discovered a clear link between Juno’s plasma waves and X-ray auroral flares observed by XMM-Newton at Jupiter’s north pole.
They utilized computer simulations to establish that the waves would propel the heavier particles into Jupiter’s atmosphere.
It’s unknown why the magnetic field lines vibrate on a regular basis, but it could be due to interactions with the solar wind or high-speed plasma flows within Jupiter’s magnetosphere.
Jupiter’s magnetic field is incredibly powerful — around 20,000 times stronger than Earth’s — and as a result, its magnetosphere, or the area influenced by this magnetic field, is enormous.
It would cover a region several times the size of our moon if visible in the night sky.
The Chinese Academy of Sciences, China’s National Natural Science Foundation, the UK’s Science and Technology Facilities Council (STFC), Royal Society, and Natural Environment Research Council, as well as ESA and NASA, all contributed to the project.
* Jupiter’s X-ray aurora alone emits about a gigawatt of energy, roughly similar to what a single power plant would produce over a few days.
Reference: Science Advances, 9 July 2021