A research team has solved a decades-old mystery about how Jupiter produces a spectacular series of X-rays every few minutes.
A research team co-led by UCL (University College London) has solved a decades-old mystery about how Jupiter produces a spectacular series of X-rays every few minutes.
The X-rays are part of Jupiter’s northern lights – eruptions of visible and invisible light that occur when charged particles interact with the planet’s atmosphere. A similar phenomenon occurs on Earth and creates the Northern Lights, but Jupiters is much more powerful and releases hundreds of gigawatts of energy, short enough to power entire human civilization. *
In a new study, published in Scientific progress, scientists combined close-up of Jupiter’s environment at NASA’s satellite Juno, which is currently orbiting the planet, with simultaneous X-rays from the European Space Agency’s XMM-Newton observatory (which is in Earth’s own orbit).
The research team, led by UCL and the Chinese Academy of Sciences, discovered that X-rays were triggered by periodic vibrations of Jupiter’s magnetic field lines. These vibrations create plasma waves (ionized gas) that send heavy ion particles “surfing” along magnetic field lines until they smash into the planet’s atmosphere and release energy in the form of X-rays.
Co-author Dr. William Dunn (UCL Mullard Space Science Laboratory) said: “We have been seeing Jupiter produce X-ray neuras for four decades, but we did not know how this happened. We only knew they were being produced when ions crashed into the planet’s atmosphere.
“Now we know that these ions are transported by plasma waves – an explanation that has not been suggested before, even though a similar process produces the Earth’s own northern lights. It could therefore be a universal phenomenon found in many different environments in space. ”
X-ray neuras occur at Jupiter’s north and south poles, often with clockwork regularity – during this observation, Jupiter produced bursts of X-rays every 27 minutes.
The charged ion particles that hit the atmosphere originate from volcanic gas flowing into space from giant volcanoes on Jupiter’s moon, Io.
This gas becomes ionized (its atoms are stripped free of electrons) due to collisions in Jupiter’s immediate environment and forms a donut of plasma surrounding the planet.
For the first time, astronomers have seen the way in which Jupiter’s magnetic field is compressed, which heats the particles and directs them along the magnetic field lines into Jupiter’s atmosphere, sparking the X-ray neurora. The connection was made by combining in situ data from NASA’s Juno mission with X-ray observations from ESA’s XMM-Newton. Credit: ESA / NASA / Yao / Dunn
Co-author Author Zhonghua Yao (Chinese Academy of Sciences, Beijing) said: “Now we have identified this basic process, there are a wealth of possibilities for where it could be studied next. Similar processes probably occur around Saturn, Uranus, Neptune and probably also exoplanets, where different kinds of charged particles ‘surf’ on the waves. ”
Co-author Professor Graziella Branduardi-Raymont (UCL Mullard Space Science Laboratory) said: “X-rays are typically produced by extremely powerful and violent phenomena such as black holes and neutron stars, so it seems strange that just planets also produce them.
“We can never visit black holes as they are outside space, but Jupiter is right outside the door. With the arrival of the Juno satellite to Jupiter’s orbit, astronomers now have a great opportunity to study an environment that produces X – ray images up close. ”
For the new study, scientists analyzed observations of Jupiter and its surrounding environment performed continuously over a 26-hour period by the Juno and XMM-Newton satellites.
They found a clear correlation between waves in the plasma detected by Juno and X-ray auroral flares at Jupiter’s north pole detected by XMM-Newton. They then used computer modeling to confirm that the waves would propel the heavy particles toward Jupiter’s atmosphere.
Why the magnetic field lines vibrate at regular intervals is unclear, but the vibration may be due to interactions with the solar wind or from high-velocity plasma currents within Jupiter’s magnetosphere.
Jupiter’s magnetic field is extremely strong – approx. 20,000 times as powerful as Earth’s – and therefore its magnetosphere, the area controlled by this magnetic field, is extremely large. If it were visible in the night sky, it would cover an area several times the size of our moon.
The work was supported by the Chinese Academy of Sciences, the National Natural Science Foundation of China and the UK’s Science and Technology Facilities Council (STFC), the Royal Society and the Natural Environment Research Council, as well as ESA and NASA.
* Jupiter’s X-ray neurora alone releases around one gigawatt, equivalent to what a power plant can produce over a period of days.
Reference: July 9, 2021, Scientific progress.
DOI: 10.1126 / sciadv.abf0851