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An international team of astronomers has successfully probed the Jovian atmosphere with the help of the Atacama Large Multimeter / Submillimeter Network (ALMA) and several ground-based optical telescopes and radio-based telescopes. space.
Spherical ALMA map of Jupiter showing the distribution of ammonia gas under Jupiter's Cloud Cloud. Image credit: ALMA / ESO / NAOJ / NRAO / I. de Pater et al / AUI / NSF / S. Dagnello.
"ALMA has enabled us to make a 3D map of the distribution of ammonia gas under clouds," said Dr. Imke de Pater, a researcher at the University of California at Berkeley.
"And for the first time, we were able to study the atmosphere beneath the layers of ammonia clouds after an energetic eruption on Jupiter."
The Jovian atmosphere is composed mainly of hydrogen and helium, as well as traces of methane, ammonia, hydrogen sulphide and water. The highest cloud layer is ammonia ice.
Underneath is a layer of solid ammonium hydrosulfide, and even more deeply, at about 80 km (80 km) below the upper cloud layer, there is probably a cloud layer of. liquid water.
The variations in the upper clouds form the distinctive brown belts and the white areas seen from the Earth.
Many storms on Jupiter take place inside these belts. They can be compared to thunderstorms on Earth and are often associated with lightning.
Storms are revealed in visible light in the form of small, shiny clouds called feathers. These plume eruptions can cause a major disruption of the belt, which can be visible for months or years.
Jupiter flat map in ALMA radio waves (top) and Hubble visible light (bottom). The eruption in the south equatorial belt is visible on both images. Image credit: ALMA / ESO / NAOJ / NRAO / I. de Pater et al / AUI / NSF / S.Dagnello / NASA / ESA / Hubble.
The radio wave images were taken by ALMA a few days after amateur astronomers observed an eruption in the southern belt of Jupiter's Equatorial in January 2017.
A small bright white plume was first visible, then a large scale disturbance in the belt lasted weeks after the eruption.
Dr. de Pater and his colleagues used ALMA to study the Jovian atmosphere under the plume and disturbed belt at radio wave lengths.
They also compared ALMA images with UV-visible light and infrared images made with other telescopes at about the same time.
"Our ALMA observations are the first to show that high concentrations of ammonia are produced during an energy eruption," said Dr. de Pater.
"The combination of observations simultaneously at many different wavelengths allowed us to examine the eruption in detail."
"This has led us to confirm the current theory that energy plumes are triggered by wet convection at the base of the water clouds, located in the depths of the atmosphere. The plumes bring ammonia from the depths of the atmosphere up to high altitudes, well above the main deck of ammonia clouds. "
"These ALMA maps at millimeter wavelengths complete the maps made with the NSF's very large network in centimetric wavelengths," said Dr. Bryan Butler, astronomer at the National Radio Astronomy Observatory.
"The two maps sound beneath the cloud layers observed at optical wavelengths and show ammonia-rich gases that rise and form the upper cloud layers (zones) and a subsidence of ammonia-poor air (belts ). "
An article describing the results will be published in the Astronomical Journal.
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Imke from Pater et al. 2019. First millimeter charts of ALMA wavelengths of Jupiter, with a convection study on several wavelengths. A J, in the press; arXiv: 1907.11820
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