Scientists have solved the 40-year-old mystery of unexplained flares observed in Jupiter’s atmosphere. It turned out that X-ray scintillations are akin to auroras on Earth and are caused by vibrations of the magnetic field.
An international team of astrophysicists, led by scientists from University College London and the Chinese Academy of Sciences , has identified the reason why Jupiter produces powerful X-ray bursts every few minutes. This is reported in the journal Science Advances .
As the researchers themselves explain, X-ray flares are part of Jupiter’s auroras – visible and invisible light that occurs when charged particles interact with the planet’s atmosphere. A similar phenomenon, scientists say, occurs on Earth in the form of the northern and southern lights.
However, on Jupiter, the auroras are much more powerful – they release hundreds of gigawatts of energy. X-rays alone emit about 1 GW, which is equivalent to the power that an average power plant on Earth generates over several days.
To reveal the mechanism behind the appearance of powerful X-ray flares on Jupiter, scientists combined data from several spacecraft at once. Especially for the observation of this planet, NASA in 2011 launched the automatic interplanetary station “Juno”, which is currently in the orbit of Jupiter. Also, in the work of the international team, data obtained by the European-American space X-ray observatory XMM-Newton were used. This unit, equipped with three powerful X-ray telescopes, has been operating in Earth orbit since late 1999.
During the study, scientists continuously observed Jupiter and its atmosphere for 26 hours. They established a direct link between plasma waves detected by Juno and X-ray flares at Jupiter’s north pole recorded by the XMM-Newton observatory. Then, using computer simulations, they made sure that the plasma waves send heavy particles towards the planet’s atmosphere.
As a result, astrophysicists were able to establish that X-ray flares arise due to periodic oscillations of the lines of force of Jupiter’s magnetic field. These vibrations in turn produce plasma (ionized gas) waves. Particles of heavy ions “float” along the lines of force of the magnetic field and crash into the planet’s atmosphere, releasing energy in the form of X-rays.
“For four decades, we watched Jupiter produce X-rays, but we did not know exactly how this happens. We only realized that the flares appeared as a result of the collision of ions with the planet’s atmosphere. We now know that these ions are carried by plasma waves. This explanation has not been previously discussed. Although a similar process is caused by the aurora on Earth. Therefore, it can be considered a universal phenomenon that is present in many different environments in space”, said one of the lead authors of the article, Dr. William Dunn of the Mallard Space Research Laboratory at University College London.
It is known that X-ray flares on Jupiter occur with a strict periodicity; at the time of observations, they were recorded every 27 minutes.
It turned out that charged particles entering the atmosphere originate on Jupiter’s moon Io. They erupt into space from its giant volcanoes.
As the researchers explain, the gas produced by the moon of Jupiter becomes ionized – its atoms are deprived of electrons. Striking the planet’s atmosphere, the gas accumulates around Jupiter in a donut-shaped layer of plasma.
For the first time, astronomers have seen Jupiter’s magnetic field contract, which heats particles and directs them along the magnetic field lines down into the planet’s atmosphere, causing X-ray bursts.
“We have now identified this fundamental process and there are many opportunities to explore it further. Similar processes, presumably, also occur around Saturn, Uranus, Neptune and, probably, around exoplanets with different types of charged particles “floating on waves”, – said one of the lead authors of the study, Dr. Yao Zhonghua of the Chinese Academy of Sciences.
Scientists note that usually X-ray bursts occur in space as a result of powerful phenomena associated with black holes or neutron stars.
Now the researchers are convinced that such flares can be produced by the planets themselves.
“We can never reach black holes because they are too far away, but Jupiter is nearby. With the arrival of the Juno satellite in Jupiter’s orbit, astronomers have a fantastic opportunity to closely study the atmosphere that produces X-rays”, summed up one of the authors of the work, Professor Graziella Branduardi-Raymond of the Mallard Space Research Laboratory at University College London.
Article written by Nikolay Gorodetsky