& # 39; Tape & # 39; Envelops the mystery of Jupiter's magnetic equator

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& # 39; Ribbon & # 39; Envelops the Mystery of Jupiter's Magnetic Equator
This image is a map of the H3 + ion infrared brilliance at the top of the Jupiter atmosphere that reveals how complex the ionosphere is . The two white regions at the top and bottom are the bright aurora of the planet. Glowing much brighter than the rest of the planet, they are so saturated here that no detail can be seen at all. Instead, the equatorial region can be seen. At the top left of the map, the previously observed darkening associated with the big cold spot can be seen – the map now shows that this dark feature is only one of many in the ionosphere. The black ribbon that ripples around the horizontal center of the image, surrounding the planet from left to right, reveals the location of Jupiter's magnetic equator. To the right of the image, above and below the black ribbon, there are two very dark regions, one larger north and one small circle south. We are not quite sure of these features, but when the Juno spacecraft measured the magnetic fields in these areas, they proved to be very abnormal – perhaps these regions are similar to the magnetic anomaly of the South Atlantic on Earth. Credit: University of Leicester

The discovery of a dark ribbon of low hydrogen ion emissions that surrounds Jupiter has upset the previous thought on the magnetic equator of the giant planet.

An international team of scientists led by the University of Leicester identified the weakened ribbon of H3 + emissions near the jovigraphic equator using the NSFCam instrument of the NASA InfraRed Telescope Facility, the first evidence of a localized ionospheric interaction with the magnetic field of Jupiter.

The study is published online by Nature Astronomy Today (July 23)

In the past, studies of the ionosphere of Jupiter have been almost exclusively focused on the poles of the planet, looking at the aurora borealis. These observations have seen most of the Jupiter ionosphere relatively smooth and uninteresting.

This latest study has opened the entire ionosphere for study and suggests that the ionosphere of Jupiter is as complex as our observations can measure with levels of detail yet to be revealed. It also demonstrates that, despite the differences in size and structure, Earth and Jupiter have a similar localized ribbon that winds around the planet's magnetic equator.

The ionosphere is the ionized part of the upper atmosphere of Jupiter. Here, collisions between photoelectrons and H2 are a significant source of H3 + ions.


& # 39; Ribbon & # 39; Envelops the Mystery of Jupiter's Magnetic Equator
The same H3 + brightness map as in redmap.jpg. However, here we have superimposed three different measurements of Jupiter's magnetic equator. The first, in blue (with the widest dashes), is the best past estimate of what was thought to be the equator using ultraviolet light; the second, in red and yellow (with medium dashes) is the location of the black ribbon seen on this map; the third is the new measure of the magnetic equator recently measured by the Juno spacecraft. This magnetic measurement shows how dark the ribbon follows the magnetic equator of Jupiter. Credit: University of Leicester
An explanation for the black ribbon is that because electrons preferentially travel along magnetic field lines, these photoelectrons are diverted to higher latitudes of the magnetic equator when they move to lower altitudes. – leaving behind the reduced production ribbon of H3 +

Recent data from NASA's Juno probe support the theory that this ribbon is a signature for Jupiter's magnetic equator.

Tom Stallard, associate professor of planetary astronomy at the University of Leicester, said: "The first time we saw the In our data, we were certain that we saw something special about Jupiter: the result was so surprising and yet clear, he took us all by surprise, and we strongly suspected and speculated that the feature was due to Jupiter's Magnetic Equator

"It was a great relief to us that a few months before the publication of our article, Jupiter's first magnetic model was released The Juno spacecraft, offering an unprecedented vision of the Jupiter equatorial magnetic field, and the measured magnetic equator aligned almost exactly with our dark ribbon

"Our observations, along with recent measurements by Juno spacecraft, have surprised us. Some of the auroral regions of Jupiter were very complex, and many earlier models predicted a very complex magnetic equator, but the magnetic equator is actually closer to Earth. allowing us to look at the ionosphere as the planet rotates as it would be seen from the Earth. The map starts with the bright aurora of Jupiter, but as the planet rotates, we show a weaker, weaker emission, so these auroras are saturating, allowing us to see much weaker features near l & # 39; equator. We highlight the Great Cold Spot that our team has discovered previously, as well as the location of the magnetic equator of Jupiter, but the map also shows a wide variety of other bright and dark areas. Credit: University of Leicester

"Scientists working with Juno have suggested that this could indicate that complex distortions in the magnetic field of Jupiter can occur at relatively shallow depths on the planet. 39 ionosphere between the equator and the pole, suggesting that the magnetic field of Jupiter in these regions is much more complex than that of the Earth, and that Juno is taking observations at higher resolution.Scientists have used 13,501 images of H3 + emissions taken for 48 nights between 1995 and 2000. This helps reveal the rate of change of Jupiter's complex magnetic field at mid-latitudes and provides insight into what is going on in depth. inside of Jupiter.He also suggests that the location of the magnetic equator of Jupiter has remained stable over the 15 years separating this Two independent measurements

The observations identified a number of other dark localized areas, including the area identified last year as the Great Cold Spot. by the same team of scientists. The Great Cold Spot is also thought to be caused by the effects of the planet's magnetic field, with its spectacular polar auroras driving energy into the atmosphere as heat circulating around the planet and creating a region cooling in the thermosphere.


Learn more:
Juno data show moons of Jupiter causing footprints in the aurora

More information:
Tom S. Stallard et al, Identification of the magnetic equator of Jupiter through H3 + ionospheric emission, Nature Astronomy (2018). DOI: 10.1038 / s41550-018-0523-z

Journal Reference:
Nature Astronomy

Source:
University of Leicester

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