High-energy X-ray emissions at Jupiter’s south pole consistently pulse every 11 minutes; meanwhile those at the gas giant’s north pole are erratic: increasing and decreasing in brightness, independent of the south pole, according to a study published in the journal Nature Astronomy. This behavior is distinct from Earth’s north and south auroras which broadly mirror each other in activity.
This image combines an image taken with the NASA/ESA Hubble Space Telescope in the optical and observations of the Jovian aurora in the ultraviolet. Image credit: NASA / ESA.
Using ESA’s XMM-Newton and NASA’s Chandra X-ray observatories in May to June 2016 and March 2007, the study authors produced maps of Jupiter’s X-ray emissions and identified an X-ray hot spot at each pole of the planet.
Each hot spot covers an area much bigger than the surface of the Earth, according to the team.
Studying each to identify patterns of behavior, the scientists found that the hot spots have very different characteristics.
“We didn’t expect to see Jupiter’s X-ray hot spots pulsing independently as we thought their activity would be coordinated through the planet’s magnetic field,” said lead author Dr. William Dunn, from the Mullard Space Science Laboratory at University College London and the Harvard-Smithsonian Center for Astrophysics.
“We need to study this further to develop ideas for how Jupiter produces its X-ray aurora and NASA’s Juno mission is really important for this.”
Artist’s impression of the Jovian aurora. Image credit: JAXA.
“The behavior of Jupiter’s X-ray hot spots raises important questions about what processes produce these auroras,” added co-author Dr. Licia Ray, of Lancaster University.
“We know that a combination of solar wind ions and ions of oxygen and sulfur, originally from volcanic explosions from Jupiter’s moon, Io, are involved. However, their relative importance in producing the X-ray emissions is unclear.”
“What I find particularly captivating in these observations, especially at the time when Juno is making measurements in situ, is the fact that we are able to see both of Jupiter’s poles at once, a rare opportunity that last occurred 10 years ago,” said co-author Professor Graziella Branduardi-Raymont, from University College London.
“Comparing the behaviors at the two poles allows us to learn much more of the complex magnetic interactions going on in the planet’s environment.”
The researchers hope to keep tracking the activity of Jupiter’s poles over the next two years using X-ray observing campaigns in conjunction with Juno to see if this previously unreported behavior is commonplace.
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W.R. Dunn et al. The independent pulsations of Jupiter’s northern and southern X-ray auroras. Nature Astronomy, published online October 30, 2017; doi: 10.1038/s41550-017-0262-6
