Researchers use VLT exoplanet hunter to study Jupiter's winds

Credit: NASA/JPL-Caltech/SwRI/MSSS. Image processing by Thomas Thomopoulos

In a research of Jupiter's winds, an equipment designed to locate planets light years distant was utilized on a solar system object for the first time.

Currently, there are over 5,000 known planets orbiting other stars, making the discovery of new ones practically routine. The majority of the initial far-off planets on this list were gigantic planets, which resembled Jupiter and Saturn but were also extremely distinct from them in many aspects.

Although astronomers have started gathering information on exoplanet atmospheres, fundamental concerns concerning the atmosphere of the largest planet in the solar system remain unanswered. Jupiter must be studied over an extended period of time through ongoing observations in order to comprehend what transpires in its clouds and air layers.

For the first time, the planet Jupiter, which is about 43 light minutes from Earth, has been targeted by an instrument designed to locate and study worlds light years distant from Earth, known as exoplanets.

The Planetary Systems research group at IA developed the current ESPRESSO method along with additional spectrographs to examine Venus's atmosphere. For a number of years, the researchers have been modeling the general atmosphere of this neighboring planet and analyzing its winds.

This method's exploratory application with a "top of the range" device like ESPRESSO has produced a success that expands our understanding of our cosmic neighborhood. This work confirms that it is possible to monitor gaseous planets' furthest atmospheres in a systematic manner.

The VLT telescope was pointed at Jupiter's equatorial zone, where light clouds are found at a higher altitude, and its north and south equatorial belts, which correlate to descending air and form bands of darker, warmer clouds in a deeper layer of the atmosphere, for five hours in July 2019.

"Ammonia, ammonium hydrosulfide, and water, which form the distinct red and white bands, are found in Jupiter's atmosphere at the level of the clouds visible from Earth," explains Pedro Machado of IA & Ciências ULisboa. "Ammonia ice makes up the upper clouds, which are found in the pressure range of 0.6 to 0.9 bars. The researcher continues, "Water clouds form the lowest, densest layer and have the strongest influence on the dynamics of the atmosphere."

The researchers measured winds on Jupiter ranging from 60 to 428 km/h with an error of less than 36 km/h using ESPRESSO. There are difficulties in applying these measurements to a gaseous planet using a high-resolution instrument: "One of the difficulties centered on 'navigation' over Jupiter's disk, that is, knowing exactly which point on the planet's disk we were pointing to, due to the enormous resolution of the VLT telescope," Pedro Machado says.

Credit: Pedro Machado.

"In the research itself, the difficulty was related to the fact that we were determining winds with an accuracy of a few meters per second when Jupiter's rotation is on the order of ten kilometers per second at the equator and, to complicate matters because it is a gaseous planet, and not a rigid body, it rotates at different speeds depending on the latitude of the point we observe," says the investigator.

In order to compare the results, the researchers also collected previous measurements to confirm the accuracy of Doppler velocimetry from Earth-based observatories in detecting Jupiter's winds. The majority of the data that is currently available was gathered using a different technique, which involved using satellite data to trace cloud patterns in photographs taken at close times to determine average wind speed numbers.

This history's congruence with the numbers obtained in the recently published study validates that Doppler velocimetry may be used to monitor Jupiter's winds from Earth.

A trustworthy model for the worldwide circulation of Jupiter's atmosphere must be developed, and the monitoring will enable the study team to gather information on how winds vary over time.

The goal of this computer model is to better understand the origins of the atmospheric phenomena we see on this planet by simulating the variations in winds based on latitude and Jupiter's storms. On the other hand, the model will provide information about the pressure and altitude of clouds in the telescope's field of view, helping to prepare future observations.

The group plans to use ESPRESSO to expand its observation coverage of Jupiter's disk and to temporally record wind data for the duration of the planet's nearly 10-hour revolution. It will also be feasible to monitor winds at various altitudes and learn more about the vertical transit of air layers by limiting observations to specific wavelength ranges.

The team intends to adapt the method to the atmospheres of other gaseous planets, with Saturn as the next target, after it has been perfected for the largest planet in the solar system.

The accomplishment of these observations with ESPRESSO proves to be significant at a time when its replacement, ANDES, is being developed for the upcoming Extremely Large Telescope (ELT), which is also being built in Chile by ESO, as well as the upcoming JUICE mission, which is being built by the European Space Agency and is intended to study Jupiter and provide more data.


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