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EI2GYB > ASTRO 30.08.21 11:27l 134 Lines 6378 Bytes #999 (0) @ WW
BID : 13887_EI2GYB
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Subj: Space scientists reveal secret behind Jupiter's 'energy cri
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Sent: 210830/0923Z 13887@EI2GYB.DGL.IRL.EURO BPQ6.0.22
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Space scientists reveal secret behind Jupiter's 'energy crisis'
New research has revealed the solution to Jupiter's 'energy crisis',
which has puzzled astronomers for decades.
Astronomers have created a detailed global map of the gas giant's
upper atmosphere, confirming that Jupiter's powerful aurorae are
responsible for delivering planet-wide heating.
New research published in Nature has revealed the solution to Jupiter's
'energy crisis', which has puzzled astronomers for decades.
Space scientists at the University of Leicester worked with colleagues
from the Japanese Space Agency (JAXA), Boston University, NASA's Goddard
Space Flight Center and the National Institute of Information and
Communications Technology (NICT) to reveal the mechanism behind Jupiter's
atmospheric heating.
Now, using data from the Keck Observatory in Hawai'i, astronomers have
created the most-detailed yet global map of the gas giant's upper
atmosphere, confirming for the first time that Jupiter's powerful
aurorae are responsible for delivering planet-wide heating.
Dr James O'Donoghue is a researcher at JAXA and completed his PhD at
Leicester, and is lead author for the research paper. He said:
"We first began trying to create a global heat map of Jupiter's
uppermost atmosphere at the University of Leicester.
The signal was not bright enough to reveal anything outside of Jupiter's
polar regions at the time, but with the lessons learned from that work
we managed to secure time on one of the largest, most competitive
telescopes on Earth some years later.
"Using the Keck telescope we produced temperature maps of extraordinary detail.
We found that temperatures start very high within the aurora, as expected
from previous work, but now we could observe that Jupiter's aurora,
despite taking up less than 10% of the area of the planet, appear to be
heating the whole thing.
"This research started in Leicester and carried on at Boston University
and NASA before ending at JAXA in Japan.
Collaborators from each continent working together made this study
successful, combined with data from NASA's Juno spacecraft in orbit
around Jupiter and JAXA's Hisaki spacecraft, an observatory in space."
Dr Tom Stallard and Dr Henrik Melin are both part of the School of
Physics and Astronomy at the University of Leicester. Dr Stallard added:
"There has been a very long-standing puzzle in the thin atmosphere at
the top of every Giant Planet within our solar system.
With every Jupiter space mission, along with ground-based observations,
over the past 50 years, we have consistently measured the equatorial
temperatures as being much too hot.
"This 'energy crisis' has been a long standing issue -- do the models
fail to properly model how heat flows from the aurora, or is there some
other unknown heat source near the equator?
"This paper describes how we have mapped this region in unprecedented
detail and have shown that, at Jupiter, the equatorial heating is directly
associated with auroral heating."
Aurorae occur when charged particles are caught in a planet's magnetic field.
These spiral along the field lines towards the planet's magnetic poles,
striking atoms and molecules in the atmosphere to release light and energy.
On Earth, this leads to the characteristic light show that forms the
Aurora Borealis and Australis.
At Jupiter, the material spewing from its volcanic moon, Io, leads to
the most powerful aurora in the Solar System and enormous heating in the
polar regions of the planet.
Although the Jovian aurorae have long been a prime candidate for
heating the planet's atmosphere, observations have previously been unable
to confirm or deny this until now.
Previous maps of the upper atmospheric temperature were formed using
images consisting of only several pixels.
This is not enough resolution to see how the temperature might be
changed across the planet, providing few clues as to the origin of the
extra heat.
Researchers created five maps of the atmospheric temperature at different
spatial resolutions, with the highest resolution map showing an average
temperature measurement for squares two degrees longitude 'high' by two
degrees latitude 'wide'.
The team scoured more than 10,000 individual data points, only mapping
points with an uncertainty of less than five per cent.
Models of the atmospheres of gas giants suggest that they work like a
giant refrigerator, with heat energy drawn from the equator towards the
pole, and deposited in the lower atmosphere in these pole regions.
These new findings suggest that fast-changing aurorae may drive waves
of energy against this poleward flow, allowing heat to reach the equator.
Observations also showed a region of localised heating in the sub-auroral
region that could be interpreted as a limited wave of heat propagating
equatorward, which could be interpreted as evidence of the process driving
heat transfer.
Planetary research at the University of Leicester spans the breadth of
Jovian system, from the planet's magnetosphere and atmosphere, out to
its diverse collection of satellites.
Leicester researchers are members of the Juno mission made up of a global
team astronomers observing the giant planet, and are leading Jupiter
observations from the forthcoming James Webb Space Telescope.
Leicester also plays a leading role in science and instrumentation on
the European Space Agency (ESA)'s Jupiter Icy Moons Explorer (JUICE), due
for launch in 2022.
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