Jupiter’s auroras

Solar storms trigger X-ray auroras on Jupiter that are about eight times brighter than normal over a large area of the planet and hundreds of times more energetic than Earth’s northern lights.

That’s according to a new study published March 22, 2016 in the Journal of Geophysical Research. The research – using data from NASA’s Chandra X-ray Observatory – is the first time Jupiter’s auroras have been studied in X-ray light when a giant solar storm arrived at the planet.

Jupiter's X-ray emission (in magenta and white, for the brightest spot, overlaid on a Hubble Space Telescope optical image) captured by Chandra as a coronal mass ejection (CME) reaches the planet on October 2, 2011, and then after the solar wind subsides on October 4, 2011. The northern lights seem to expand southwards and the brightening is clearly visible as the CME arrives. Image via Joseph DePasquale, Smithsonian Astrophysical Observatory Chandra X-ray Center.
These composite images show Jupiter and its aurora. The impact of the CME on Jupiter’s aurora was tracked by monitoring the X-rays emitted during two 11-hour observations. The scientists used that data to pinpoint the source of the X-ray activity and identify areas to investigate further at different time points. The images show Jupiter’s X-ray emission (in magenta and white, for the brightest spot, overlaid on a Hubble Space Telescope optical image) captured by Chandra as a coronal mass ejection (CME) reaches the planet on October 2, 2011, and then after the solar wind subsides on October 4, 2011. The northern lights seem to expand southwards and the brightening is clearly visible as the CME arrives. Image credit: NASA

The sun constantly ejects streams of particles into space in the solar wind. Sometimes, giant storms, known as known as coronal mass ejections (CMEs), erupt and the winds become much stronger. These events compress Jupiter’s magnetosphere, the region of space controlled by Jupiter’s magnetic field, shifting its boundary with the solar wind inward by more than a million miles. This new study suggests that the interaction at the boundary triggers the X-rays in Jupiter’s auroras, which cover an area bigger than the surface of the Earth.

William Dunn is PhD student at University College London’s Mullard Space Science Laboratory and the study’s lead author. Dunn said:

There’s a constant power struggle between the solar wind and Jupiter’s magnetosphere.

We want to understand this interaction and what effect it has on the planet. By studying how the aurora changes, we can discover more about the region of space controlled by Jupiter’s magnetic field, and if or how this is influenced by the sun. Understanding this relationship is important for the countless magnetic objects across the galaxy, including exoplanets, brown dwarfs and neutron stars.

The impact of solar storms on Jupiter’s aurora was tracked by monitoring the X-rays emitted during two 11-hour observations in October 2011 when an interplanetary coronal mass ejection was predicted to reach the planet from the sun. The scientists used the data collected to build a 3D spherical image to pinpoint the source of the X-ray activity and identify areas to investigate further at different time points. Dunn said:

In 2000, one of the most surprising findings was a bright ‘hot spot’ of X-rays in the aurora which rotated with the planet. It pulsed with bursts of X-rays every 45 minutes, like a planetary lighthouse.

When the solar storm arrived in 2011, we saw that the hot spot pulsed more rapidly, brightening every 26 minutes. We’re not sure what causes this increase in speed but, because it quickens during the storm, we think the pulsations are also connected to the solar wind, as well as the bright new aurora.

EarthSky // Science Wire, Space Release Date: Mar 24, 2016
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Source: Solar storms ignite Jupiter’s auroras | Science Wire | EarthSky

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