Key Highlights:
- From the Io volcanic moon Jupiter’s auroras produce notable X-ray flares
- Scientists first noticed this mismatch more than 40 years ago
- The researchers examined Jupiter with the 10-meter Keck II telescope over Hawaiian inactive Mauna Kea Volcano
Jupiter’s Aurora Producing Impressive X-ray Flares
An aurora is a natural light show in the Earth’s sky, usually seen in high latitude zones (around the Arctic and Antarctic). Auroras feature dynamic patterns of light, which seem like curtains, rays, spirals, or dynamic flickers that span the whole sky. The majority of solar system planets, some natural satellites, brown dwarves, and comets also host aurora.
Jupiter’s aurora generates remarkable X-ray flares from Jupiter’s volcanic moon Io. They come from electrically charged sulfur and oxygen ions. Jupiter’s X-ray auroras alone each discharge around a gigawatt, about what one power station on Earth might generate throughout several days. These X-ray auroras frequently pulse like clockwork, in regular beats of a few dozen minutes for dozens of hours.
After a decade of research, a scientist may have drawn up a possible source of the unusual heat. The culprit, according to a new study, is the planet’s powerful aurora, Jupiter’s version of Earth’s northern and southern lights.
Investigators Employes the 10-meter Keck II Telescope
“The temperature of Jupiter’s upper environment, which orbits the sun at an average distance of 778 million kilometers, should be approximately-73 degrees Celsius,” states James O’Donoghue, a planetary scientist at the JAXA Institute of Space and Astronautical Sciences in Sagamihara, Japan. That’s mainly due to the low lighting of the sun there, which represents less than 4% of the energy per square meter that affects the atmosphere of the Earth. However, the region that is multiple hundred kilometers above the planet’s cloud tops has an average temperature of roughly 426° C.
Scientists first noticed this mismatch more than 40 years ago. Since then, they have come up with many suggestions about the source of the thermal boost in the upper atmosphere, including pressure waves or waves of gravity generated by turbulence lower in the atmosphere. However, investigations by O’Donoghue and colleagues now provide convincing proof that auroras pump heat in the upper atmosphere of the planet.
The investigators employed the 10-meter Keck II telescope above the Hawaii dormant Mauna Kea Volcano to examine Jupiter on one night each in 2016 and 2017. In particular, the scientists searched for infrared emissions that betray the existence of hydrogen molecules with positive charges (H3+). These molecules are generated when charged particles in the Solar Wind slam hundreds of thousands of kilometers per second into the atmosphere of the Earth, painting polar auroras.
Researchers Observe Jupiter One Night
Measuring the intensities of these molecules’ infrared emissions allowed researchers to determine how hot it is above the cloud tops. Temperatures in the upper atmosphere reached approximately 725° C in these arctic locations, the team reported on 5 August. However, the team’s heat map showed the temperature at equatorial latitudes dropped to roughly 325°C. This pattern of a gradual reduction in temperature in the lower latitudes reinforces the assumption that the auroras of Jupiter are the origin of abnormal heat in the higher atmosphere and that winds are dispersed from the polar regions.
One of the nights Jupiter was watched by the researchers – 25 January 2017 – was particularly timely because Jupiter had a powerful solar outburst at that moment. In addition to the powerful aurora, measurements revealed a broad range of warmer than normal medium latitudinal gases, which researchers consider to be a wave of warmth that rolls southward. “It was pure luck that we captured this potential heat-shedding event,” says O’Donoghue.
The group’s observations “are close to a’smoking gun’ to disseminate the aura energy,” says Tommi Koskinen, a planetary scientist at the University of Arizona in Tucson. The next challenge, he emphasizes, is to understand the underlying heat generation and heat transmission mechanisms and then integrate them into researchers’ simulations of Jupiter’s atmospheric circulation.
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