Besides displaying the most spectacular volcanic activity in the solar system, Io causes auroras on its mother planet that are similar to the Northern Lights on Earth. The auroral emissions linked to the volcanic moon are called the Io footprint.
From previous studies, researchers had found the Io footprint to be a bright spot that is often followed by other auroral spots. Those spots are typically located downstream relative to a flow of charged particles around the giant planet. Now, a team of planetologists from Belgium and Germany have discovered that Io’s footprint can include a faint spot unexpectedly upstream of the main spot.
Each appearance of such a “leading spot” occurs in a distinctive pattern, the scientists say: When the main footprint is preceded by a leading spot in the northern or southern hemisphere of Jupiter, it is also followed by downstream spots in the opposite hemisphere.
“Previously, we only observed downstream spots, but only half of the configurations of Io in the Jovian magnetic field had been studied,” says Bertrand Bonfond of the University of Liège in Belgium, who is a member of the team that found the new type of spot. “Now we have the complete picture. The results are surprising because no theory predicted upstream spots.”
Like a rock in a stream, Io obstructs the flow of charged particles, or plasma, around Jupiter. As the moon disrupts the flow, it generates powerful plasma waves that blast electrons into Jupiter’s atmosphere, creating the auroral spots.
The finding of the leading spot puts all the previous models of the Io footprint into question, Bonfond says. He and his colleagues propose a new interpretation in which beams of electrons travel from one Jovian hemisphere to the other.
The new results were published online on 15 March in Geophysical Research Letters, a journal of the American Geophysical Union. The 16 March print edition of the journal features an image from the study on its cover.
For this latest Io-footprint analysis, Bonfond and his colleagues at Liège and at the University of Cologne in Germany used the Hubble Space Telescope to observe Jupiter in ultraviolet wavelengths.
New insights regarding Io-Jupiter interactions could apply to other situations in which an electrically conductive body—in this case, Io—orbits near a magnetised body, Bonfond says. Such configurations could be very common in the universe. For example, some of the recently discovered exoplanets that orbit stars other than the Sun are thought to be in such configurations with their parent stars.
Our Moon does not create a footprint on Earth because the Moon is not conductive and is also too far from the Earth, Bonfond notes.
In order to test their new theory of how leading and downstream spots form, Bonfond and his colleagues plan further observations of Io’s footprint after August 2008. That’s when repairs and improvements to the Hubble Space Telescope are scheduled to occur.
In times of climate change: What a lake’s colour can tell about its condition
21.09.2017 | Leibniz-Institut für Gewässerökologie und Binnenfischerei (IGB)
Did marine sponges trigger the ‘Cambrian explosion’ through ‘ecosystem engineering’?
21.09.2017 | Helmholtz-Zentrum Potsdam - Deutsches GeoForschungsZentrum GFZ
Plants and algae use the enzyme Rubisco to fix carbon dioxide, removing it from the atmosphere and converting it into biomass. Algae have figured out a way to increase the efficiency of carbon fixation. They gather most of their Rubisco into a ball-shaped microcompartment called the pyrenoid, which they flood with a high local concentration of carbon dioxide. A team of scientists at Princeton University, the Carnegie Institution for Science, Stanford University and the Max Plank Institute of Biochemistry have unravelled the mysteries of how the pyrenoid is assembled. These insights can help to engineer crops that remove more carbon dioxide from the atmosphere while producing more food.
A warming planet
Our brains house extremely complex neuronal circuits, whose detailed structures are still largely unknown. This is especially true for the so-called cerebral cortex of mammals, where among other things vision, thoughts or spatial orientation are being computed. Here the rules by which nerve cells are connected to each other are only partly understood. A team of scientists around Moritz Helmstaedter at the Frankfiurt Max Planck Institute for Brain Research and Helene Schmidt (Humboldt University in Berlin) have now discovered a surprisingly precise nerve cell connectivity pattern in the part of the cerebral cortex that is responsible for orienting the individual animal or human in space.
The researchers report online in Nature (Schmidt et al., 2017. Axonal synapse sorting in medial entorhinal cortex, DOI: 10.1038/nature24005) that synapses in...
Whispering gallery mode (WGM) resonators are used to make tiny micro-lasers, sensors, switches, routers and other devices. These tiny structures rely on a...
Using ultrafast flashes of laser and x-ray radiation, scientists at the Max Planck Institute of Quantum Optics (Garching, Germany) took snapshots of the briefest electron motion inside a solid material to date. The electron motion lasted only 750 billionths of the billionth of a second before it fainted, setting a new record of human capability to capture ultrafast processes inside solids!
When x-rays shine onto solid materials or large molecules, an electron is pushed away from its original place near the nucleus of the atom, leaving a hole...
For the first time, physicists have successfully imaged spiral magnetic ordering in a multiferroic material. These materials are considered highly promising candidates for future data storage media. The researchers were able to prove their findings using unique quantum sensors that were developed at Basel University and that can analyze electromagnetic fields on the nanometer scale. The results – obtained by scientists from the University of Basel’s Department of Physics, the Swiss Nanoscience Institute, the University of Montpellier and several laboratories from University Paris-Saclay – were recently published in the journal Nature.
Multiferroics are materials that simultaneously react to electric and magnetic fields. These two properties are rarely found together, and their combined...
19.09.2017 | Event News
12.09.2017 | Event News
06.09.2017 | Event News
22.09.2017 | Life Sciences
22.09.2017 | Medical Engineering
22.09.2017 | Physics and Astronomy