Swirling clouds, big colorful belts, huge storms. The beautiful and incredibly turbulent atmosphere of Jupiter has been shown many times. But what is going on under the clouds? What causes the many storms and eruptions we see on the "surface" of the planet? To investigate this, however, visible light is not enough. We have to study Jupiter with the help of radio waves.
New radio-wave images taken with the Atacama Large Millimeter / Submillimeter Array (ALMA), the most complex astronomical observatory ever built on Earth, provide a unique view of the Jupiter's atmosphere to within fifty kilometers below visible (ammonia) cloud cover of the planet.
"With ALMA we were able to map the distribution of ammonia gas under the clouds three-dimensionally. And for the first time we were able to study the atmosphere under the ammonia cloud layers after an energetic eruption on Jupiter, "said Imke de Pater of the University of California, Berkeley (EE, UU).
The atmosphere of The Giant Jupiter consists mainly of hydrogen and helium as well as trace gases of methane, ammonia, hydrogen sulfide and water. The uppermost cloud layer consists of ammonia ice. Below that is a layer of solid ammonium hydrosulphide particles, and even deeper, about 80 kilometers below the upper cloud deck, is probably a layer of liquid water. The upper clouds form the characteristic brown belts and white zones that are seen from the earth.
Many of the storms on Jupiter take place in these belts. They can be compared to thunderstorms on Earth and are often associated with lightning events. Storms appear in the visible light as small bright clouds, called feathers. These plume eruptions can cause a severe disruption to the belt, which can be visible for months or years.
The ALMA images were taken a few days after amateur astronomers observed an eruption in the southern Jupiter equator belt in January 2017. At first a small bright white cloud was visible, and then a large break in the belt was observed, which took weeks after the eruption.
De Pater and her colleagues used ALMA to study the atmosphere under the cloud and the jumbled belt at radio wavelengths and compare them to UV-visible light and infrared images taken with other telescopes at around 20 ° C Simultaneously.
"Our ALMA observations are the first to show that high levels of ammonia gas are produced during an energetic eruption," said de Pater. "Combining observations simultaneously at many different wavelengths allowed us to study the eruption in detail. This has led us to confirm the current theory that energetic feathers are triggered by moist convection at the base of water clouds that are deep in the atmosphere. The flags bring ammonia gas from the depths of the atmosphere to high altitudes, far above the main ammonia cloud cover.
These millimeter-wave ALMA maps complement the maps created with the National Science Foundation's Very Large Array in centimeter wavelength, "said Bryan Butler of the National Radio Astronomy Observatory. "Both maps examine the cloud layers visible at optical wavelengths and show ammonia-rich gases that rise and form in the upper cloud layers (zones) and low-ammonia air that sinks down (belt)."
"The present results are an excellent demonstration of what can be achieved in planetary research by examining an object with different observatories and at different wavelengths," explains Eric Villard, an ALMA astronomer in the research team. "ALMA, with its unprecedented sensitivity and spectral resolution at radio wavelengths, has successfully collaborated with other major observatories around the world to provide the data to better understand the atmosphere of Jupiter."
The Atacama Large Millimeter / Submillimeter Array (ALMA), an international astronomy facility, is a partnership of the European Southern Observatory (ESO), the US National Science Foundation (NSF), and the National Institutes of Natural Sciences (NINS) in Japan in collaboration with the Republic of Chile. ALMA is funded by ESO on behalf of its Member States, by NSF in collaboration with the National Research Council of Canada (NRC) and the Ministry of Science and Technology (MOST) in Taiwan, and by NINS in collaboration with Academia Sinica (AS). in Taiwan and the Korea Astronomy and Space Science Institute (KASI).
The construction and operation of ALMA is managed by ESO on behalf of its Member States. from the National Radio Astronomy Observatory (NRAO), managed by Associated Universities, Inc. (AUI), on behalf of North America; and the National Astronomical Observatory of Japan (NAOJ) for East Asia. Joint ALMA Observatory (JAO) provides unified management and management of ALMA's construction, commissioning and operations.