Starship Asterisk*

HEAPOW: Crowns of Jupiter Revealed (2021 Jul 12)

Like earth, Jupiter has its own version of the northern and southern lights, the aurorae. These lights are produced by the interaction of ions from space and the planet's atmosphere near the north and south magnetic poles. Jupiter's aurora is much more powerful than earth's, strong enough to generate X-rays. Jupiter's X-ray aurora also pulsates, and oddly, the southern aurora seems to pulse fairly regularly, while the northern aurora varies more randomly. The origin of the X-ray aurora, and its strange behavior, has been a longstanding mystery. But now, thanks to a long observation with the XMM-Newton X-ray observatory, and observations by Juno (a satellite mission in orbit around Jupiter), coupled with computer simulations, scientists have finally unraveled the 40-year old mystery of Jupiter's pulsating X-ray aurorae. These combined studies show that the interaction between Jupiter's strong magnetic field and the wind of particles from the sun trigger Jupiter-sized electromagnetic waves above the planet. These waves cause electrically-charged sulfur ions, produce by volcanic eruptions on Jupiter's moon Io and trapped in Jupiter's magnetic field, to periodically fall along the magnetic field lines towards Jupiter's magnetic poles. The illustration above shows how trapped ions (not to scale!) travel along Jupiter's magnetic field towards the magnetic polls, to create the X-ray aurorae. Understanding this process helps scientists understand where similar ion-magnetic field interactions might work around other planets, and elsewhere in space.

The 40-year-old mystery of what causes Jupiter’s X-ray auroras has been solved. For the first time, astronomers have seen the entire mechanism at work – and it could be a process occurring in many other parts of the Universe too.

Click to play embedded YouTube video.

Jupiter’s Mysterious X-ray Auroras Explained ~ Credit: ESA/NASA/Yao/Dunn

---

Planetary astronomers have studied Jupiter’s spectacular X-ray auroral emission for decades. The X-ray ‘colours’ of these auroras show that they are triggered by electrically charged particles called ions crashing into Jupiter’s atmosphere. But astronomers had no idea how the ions were able to get to the atmosphere in the first place.

Now, for the first time, they have seen the ions ‘surfing’ electromagnetic waves in Jupiter’s magnetic field, down into the atmosphere.

The vital clues came from a new analysis of data from ESA’s XMM-Newton telescope and NASA’s Juno spacecraft. Situated in Earth’s orbit, XMM-Newton makes remote observations of Jupiter at X-ray wavelengths. Juno on the other hand circles the giant planet itself, taking in-situ readings from inside Jupiter’s magnetic field. But the question was: what should the team look for?

The clue came when Zhonghua Yao ... realised that something didn’t make sense about Jupiter’s X-ray auroras. ...

• Science Advances 7(28):eabf0851 (09 Jul 2021) DOI: 10.1126/sciadv.abf0851

• Science Advances 7(15):eabd1204 (09 Jul 2021) DOI: 10.1126/sciadv.abd1204
• arXiv.org > physics > arXiv:2006.14834 > 26 Jun 2020