Astronomers observe a plasma show in Jupiter’s atmosphere

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Summarize this content to 100 words NASA’s Juno spacecraft, moving through the orbit of Jupiter, constantly encounters huge plasma waves. These waves are known as Kelvin-Helmholtz instabilities and arise when the solar wind plasma interacts with the planet’s magnetopause, the outer layer of its magnetic field. The difference in the speeds of the magnetopause and the solar wind creates a powerful wave, or vortex.”The Kelvin-Helmholtz instability can be observed at the boundary separating the planet’s magnetic field (magnetosphere) from the flow of charged particles emitted by the Sun (solar wind); this boundary is known as the magnetopause,” says a study published recently in the journal Geophysical Research Letters.Previously, these phenomena were known to occur on Earth and other planets and were assumed to occur on Jupiter. But their presence on the gas giant was not confirmed until Juno spotted them. The probe spent so much time at Jupiter’s dawn magnetopause that it was able to observe more of them than any other spacecraft or telescope. Now, a team of researchers from Southwest Research Institute and the University of Texas at San Antonio has analyzed Juno’s data and studied the waves in detail.Plasma teeming with charged particles is constantly dispersed throughout the Solar System by the solar wind and inevitably interacts with plasma in the outer atmospheres of the planets. Jupiter is surrounded by a rotating disk of plasma that reaches its outer magnetosphere. In this place, on the border between the planet’s magnetopause and the solar wind, magnetic tension arises. This tension causes the plasma to have regional differences in speed and direction of motion, called velocity shear.If the velocity shift exceeds the magnetic stress, then the magnetopause boundary is violated, and waves begin to form. This can happen not only with plasma from an external source, for example, a star, but also with plasma from the magnetopause located at the level of the magnetosphere directly below it. There is a special high-speed shear flow between the plasma in Jupiter’s magnetosphere and its magnetosphere, which is just above the magnetopause. This shift is infuriating.The waves that arise during such disturbances begin to collapse and eventually turn into huge eddies. Although KH waves have only been observed on Jupiter’s dawn side, it is possible that they are formed on the twilight side as well.”Periodic oscillations suggest that the spacecraft is moving through a wave structure, possibly a coiled vortex,” the study also says. “The spacecraft enters and exits the magnetosphere and magnetosphere plasma during its orbit, crossing the boundary several times.”With the help of ultra-sensitive instruments, Juno managed to detect plasma waves invisible under other conditions. The Jovian Auroral Distributions Experiment (JADE) consists of an electronics unit and four sensors: three to find electrons and one to detect ions, another plasma component. JADE sensors are able to record information about the energy and location of these charged particles as they pass through the plasma. The magnetometers on Juno’s Magnetic Field Survey (MAG) suite measure the strength of Jupiter’s magnetic field, which determines whether it can be overcome by plasma from the solar wind and thus generate a wave.The plasma wave vortices observed by Juno are thought to push more charged particles across the magnetopause, and the Juno data showed that most of the time the probe crossed the magnetopause at dawn on Jupiter, conditions were favorable for Kelvin-Helmholtz waves to form. However, this does not mean that the waves have actually occurred. Juno detected signs of waves in only 19 crossings, so there remains some uncertainty about how often waves occur under the right conditions.

Astronomers observe a plasma show in Jupiter’s atmosphere

NASA’s Juno spacecraft, moving through the orbit of Jupiter, constantly encounters huge plasma waves. These waves are known as Kelvin-Helmholtz instabilities and arise when the solar wind plasma interacts with the planet’s magnetopause, the outer layer of its magnetic field. The difference in the speeds of the magnetopause and the solar wind creates a powerful wave, or vortex.

“The Kelvin-Helmholtz instability can be observed at the boundary separating the planet’s magnetic field (magnetosphere) from the flow of charged particles emitted by the Sun (solar wind); this boundary is known as the magnetopause,” says a study published recently in the journal Geophysical Research Letters.

Previously, these phenomena were known to occur on Earth and other planets and were assumed to occur on Jupiter. But their presence on the gas giant was not confirmed until Juno spotted them. The probe spent so much time at Jupiter’s dawn magnetopause that it was able to observe more of them than any other spacecraft or telescope. Now, a team of researchers from Southwest Research Institute and the University of Texas at San Antonio has analyzed Juno’s data and studied the waves in detail.

Plasma teeming with charged particles is constantly dispersed throughout the Solar System by the solar wind and inevitably interacts with plasma in the outer atmospheres of the planets. Jupiter is surrounded by a rotating disk of plasma that reaches its outer magnetosphere. In this place, on the border between the planet’s magnetopause and the solar wind, magnetic tension arises. This tension causes the plasma to have regional differences in speed and direction of motion, called velocity shear.

If the velocity shift exceeds the magnetic stress, then the magnetopause boundary is violated, and waves begin to form. This can happen not only with plasma from an external source, for example, a star, but also with plasma from the magnetopause located at the level of the magnetosphere directly below it. There is a special high-speed shear flow between the plasma in Jupiter’s magnetosphere and its magnetosphere, which is just above the magnetopause. This shift is infuriating.

The waves that arise during such disturbances begin to collapse and eventually turn into huge eddies. Although KH waves have only been observed on Jupiter’s dawn side, it is possible that they are formed on the twilight side as well.

“Periodic oscillations suggest that the spacecraft is moving through a wave structure, possibly a coiled vortex,” the study also says. “The spacecraft enters and exits the magnetosphere and magnetosphere plasma during its orbit, crossing the boundary several times.”

With the help of ultra-sensitive instruments, Juno managed to detect plasma waves invisible under other conditions. The Jovian Auroral Distributions Experiment (JADE) consists of an electronics unit and four sensors: three to find electrons and one to detect ions, another plasma component. JADE sensors are able to record information about the energy and location of these charged particles as they pass through the plasma. The magnetometers on Juno’s Magnetic Field Survey (MAG) suite measure the strength of Jupiter’s magnetic field, which determines whether it can be overcome by plasma from the solar wind and thus generate a wave.

The plasma wave vortices observed by Juno are thought to push more charged particles across the magnetopause, and the Juno data showed that most of the time the probe crossed the magnetopause at dawn on Jupiter, conditions were favorable for Kelvin-Helmholtz waves to form. However, this does not mean that the waves have actually occurred. Juno detected signs of waves in only 19 crossings, so there remains some uncertainty about how often waves occur under the right conditions.

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