Even though the James Webb Space Telescope has replaced HubbleHubble and expanded the boundaries of our knowledge of distant galaxies and exoplanets, we haven't heard the last of the Hubble Telescope yet. If only because old archived observations await the ingenuity of astrophysicists to derive new information with new ideas and new data analysis techniques, and why not with the help of the IAIA.
We see a new example today with the publication of an article, available to view on arXiv, from an international team of astronomers. The newly processed observations were taken with Hubble in 2016, 2018 and 2019 using its Wide Field Camera 3 (WFC 3).
This is the exoplanet WASP-121 b, which has been the subject of several articles on Futura in recent years and whose name suggests that it was part of WASP (Wide Angle Search for Planets). ) has been discovered. ), a project to search for exoplanets using the astronomical transit method, an astronomical transit carried out with two identical instruments installed at the sites of two observatories, namely the Roque de los Muchachos Observatory and the Southern Astronomical Observatory-African.
A planetary atmosphere has a spectral signature that represents its chemical composition, but also its cloud and “mist” composition. Thanks to various techniques, it is possible to determine the physicochemical properties of the atmosphere of an exoplanet. These techniques include: spectroscopic transit, secondary transit or eclipse, direct spectroscopic observation of the planet, or even observation of the planet in different phases around the star to measure temporal and seasonal variations. Discover exoplanets in our 9-part web series, available on our YouTube channel. A playlist proposed by the CEA and the University of Paris-Saclay as part of the European research project H2020 Exoplanets-A. © CEA
The Meteorology of an Ultra-Hot Jupiter
Remember, this is a hot Jupiter, a hot Jupiter, and even ultra-hot, rotating synchronously around a star in the Southern Hemisphere constellation and located about 880 light-years from the Solar System. Because it is slightly more massive and larger than Jupiter, it always faces the same side to its host star, around which it completes its orbit in about 30 hours, which explains why its daily area is increased to almost 3,000 Kelvinskelvin.
Hubble's observations concern transits in front of and behind the star (see video above), which is nicknamed Dilmun (kur.dilmun.na in Sumerian, Tilmun in Akkadian), in reference to a region mentioned in the history of ancient Mesopotamia, namely WASP-121 was nicknamed Tylos, the Greek name for Bahrain, a small island nation in Arabia, near the west coast of the Persian Gulf in the Middle East. In fact, Tylos also refers to Dilmun.
The light emitted by Tylos was also recorded by WFC 3 during its phases, such as those of VenusVenus, in orbit around Dilmun.
Ultimately, the data collected could be compared to that of an atmospheric model with gas flows, temperature changes and chemical composition of Tylos. The researchers then discovered that they were actually observing signs of meteorological change in WASP-121 b's atmosphere over several years.
This video shows the 130-day temperature forecast for the exoplanet Tylos at sunrise, noon, sunset and midnight. The brightest yellow regions represent areas on the dayside of the exoplanet where the temperature rises well above 2,000 Kelvin due to proximity to its parent star, which is about 2.6% of the distance between Earth and the Sun. Due to the extreme temperature difference between the day and night sides, astronomers suspect that vaporized iron and other heavy metals that escape into the upper layers of the atmosphere on the day side partially fall back into the lower layers and rain iron on the night side. Some heavy metals also escape the planet's gravity from the upper atmosphere. © NASA, ESA, Q. Changeat et al., M. Zamani (ESA, Hubble)
Hurricanes destroyed and created in the atmosphere of an exoplanet
One of the team's principal investigators, Quentin Changeat, ESAESA researcher at the Space Telescope Science Institute, specifies in a NASA press release on the subject: “Our data set represents a significant period of observation for a single planet and is currently the only consistent set.” repeated observations of this type. The information we gained from these observations was used to characterize the atmosphere of WASP-121 b at different times (infer the chemistry, temperature and clouds). This gave us an exquisite picture of the planet changing over time. “.
The press release also states: “The models suggested that their results could be explained by quasi-periodic weather conditions, particularly massive cyclones that repeatedly form and destroy due to the huge temperature difference between the side facing the stars and the dark side of the exoplanet become.” . This result represents a significant advance in the possible observation of weather conditions on exoplanets.”
Quentin Changeat adds: “Earth's weather is responsible for many aspects of our lives, and in fact the long-term stability of Earth's climate and weather is probably the reason life was able to emerge in the first place.” Studying the weather of exoplanets is critical to understanding the complexity of exoplanet atmospheres, particularly in our search for exoplanets with habitable conditions. »
However, this is all just the beginning and both Hubble and Webb will allow us to advance even further in the field of comparative planetary science.