Researchers use the VLT exoplanet hunter to study Jupiter’s wind

Image of Jupiter taken by NASA’s Juno spacecraft in February 2022. The dark area is the shadow of the moon Ganymede. The colorful patterns are formed by clouds at different altitudes and are composed mainly of ammonia ice, ammonium hydrosulfide and water. Credit: NASA/JPL-Caltech/SwRI/MSSS. Image processing by Thomas Thomopoulos

For the first time, an instrument to find planets light years away was used on an object in the solar system, in a study of Jupiter’s wind.

We find ourselves in an era where the discovery of planets orbiting another star has become commonplace, with over 5,000 already registered. The first distant worlds included in this list are usually giant planets, similar to but also very different in many ways from Jupiter and Saturn.

Astrophysicists have begun to obtain data on the atmospheres of exoplanets, but fundamental questions about the atmosphere of the largest planet in the solar system remain unanswered. To understand what happens to Jupiter’s clouds and wind, it is necessary to study it over time with continuous observations.

For the first time, an instrument has been developed to detect and analyze worlds that are light years away, exoplanets, aimed at a target in the solar system, 43 light minutes from Earth: the planet which is Jupiter.

Researchers from the Institute of Astrophysics and Space Sciences (IA) of the Faculty of Sciences of the University of Lisbon (Portugal) (Cincias ULisboa) used the ESPRESSO spectrograph installed on the VLT telescope of the European Southern Observatory (ESO) to measure the speed of Jupiter’s wind. The results are published today in the journal universe.

The method developed by the team is called Doppler velocimetry and is based on the reflection of visible light from the sun by clouds in the atmosphere of the target planet. This reflected light is bent in wavelength in proportion to the speed of the clouds movement relative to the telescope on Earth. It gives instant wind energy at the observed point.

The method currently used by ESPRESSO was developed by the IA’s Planetary Systems research group, along with other spectrographs, to study the atmosphere of Venus. Researchers have been measuring the atmosphere of this neighboring planet and contributing to the modeling of its overall atmosphere for many years.

The exploratory use of this method with a “top of the range” instrument such as ESPRESSO resulted in a breakthrough that opened new perspectives to the knowledge of our cosmic neighborhood. This work proves the possibility of systematic monitoring of the most distant atmospheres of gaseous planets.

For five hours in July 2019, the team pointed the VLT telescope at Jupiter’s equatorial zone, where light clouds are located at higher altitudes, and at the north and south equatorial belts of this planet, which corresponds to the descending air and where it is. forming bands of darker, warmer clouds in the deeper layers of the atmosphere.

Jupiter is targeted by the exoplanet hunter

ESPRESSO spectrograph control console, during the observation of Jupiter using one of the VLT telescopes, at the Paranal Observatory, in Chile. Credit: Pedro Machado.

“Jupiter’s atmosphere, at the level of clouds visible from Earth, contains ammonia, ammonium hydrosulfide and water, which form distinct red and white bands,” said Pedro Machado, from IA and Cincias ULisboa, “The upper clouds, located in the pressure zone of 0.6 to 0.9 bar, are made of ammonia ice. Water clouds are the densest, lowest layer, and have the strongest influence on the dynamics of the atmosphere, ” added the researcher.

With ESPRESSO, the team was able to measure Jupiter’s wind from 60 to 428 km/h with an uncertainty of less than 36 km/h. These observations, used with a high-resolution instrument on a gaseous planet, have their challenges: “One of the difficulties centered on the ‘navigation’ of Jupiter’s disk, that is, knowing which point of the planet’s disk we are targeting, because of the very large resolution of the VLT telescope,” explained Pedro Machado.

“In the research itself, the difficulty is related to the fact that we determine the winds with a precision of a few meters per second when Jupiter’s rotation is in the order of ten kilometers per second at the equator and, to complicate the matter because it is a gaseous planet, and not a solid body, it rotates at different speeds depending on the latitude of the point we observe,” added the researcher.

To verify the effectiveness of Doppler velocimetry from telescopes on Earth in measuring Jupiter’s wind, the team also gathered measurements obtained in the past to compare the results. Most of the current data are collected by space instruments and use a different method, which consists of obtaining the average values ​​of the wind speed by following the cloud patterns in the images obtained in close periods. .

The consistency between this history and the values ​​measured in the study published today confirms the possibility of implementing Doppler velocimetry in a program for monitoring Jupiter’s wind from Earth.

The monitoring will allow the research team to collect data on how the wind changes over time and is essential for developing a reliable model for the global circulation of Jupiter’s atmosphere.

This computational model should reproduce the wind variations depending on latitude and storms on Jupiter to help understand the causes of the atmospheric phenomena we observe on this planet. On the contrary, the model helps prepare future observations with information about the pressure and altitude of the clouds in the telescope’s sights.

The team intends to expand the observations with ESPRESSO to a greater coverage of the planet Jupiter’s disk, as well as to temporarily collect wind data on the entire planet during the entire rotation period, which is about 10 hours. Restricting the observations to certain ranges of wavelengths also makes it possible to measure the wind at different heights, thus obtaining information on the vertical transport of the air layers.

Once the technique has been mastered for the largest planet in the solar system, the team hopes to apply it to the atmospheres of other gaseous planets, with Saturn as the next target.

The success of these observations with ESPRESSO proved to be important at a time when its successor, ANDES, was designed for the future Extremely Large Telescope (ELT), also from ESO and currently being built in Chile, but also for the future JUICE mission, from the European Space Agency, dedicated to Jupiter and which will provide additional data.

More information:
Pedro Machado et al, Jupiter’s Atmosphere Dynamics Based on High-Resolution Spectroscopy with VLT/ESPRESSO, universe (2023). DOI: 10.3390/universo9120491

Given by the University of Lisbon

Citation: Researchers use VLT exoplanet hunter to study Jupiter’s wind (2023, December 22) Retrieved December 22, 2023 from hunter-jupiter.html

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