NASA’s Hubble observes exoplanet’s atmosphere changing over three years

By combining years of observations with NASA’s Hubble Space Telescope and computer modeling, astronomers have found evidence of giant cyclones and other dynamic weather activity swirling on a hot Jupiter-sized planet 880 light-years away. I discovered.

The planet, called WASP-121 b, is not habitable. But the results are an important early step in studying weather patterns on distant worlds and ultimately discovering potentially habitable exoplanets with stable long-term climates.

Over the past few decades, detailed observations of our solar system’s neighboring planets with telescopes and spacecraft have shown that their turbulent atmospheres are not static, but constantly changing, much like Earth’s weather. It has been. This variation should also apply to planets around other stars. However, actually measuring such changes requires many detailed observations and computational modeling.

To make this discovery, an international team of astronomers assembled and reprocessed Hubble observations of WASP-121 b taken in 2016, 2018, and 2019.

They discovered that the planet has a dynamic atmosphere that changes over time. Using sophisticated modeling techniques, the research team demonstrated that these dramatic temporal variations can be explained by weather patterns in the exoplanet’s atmosphere.

The research team found that WASP-121 b’s atmosphere showed significant differences between observations. Most dramatically, the large temperature difference between the star-facing and dark side of an exoplanet can lead to repeated and destructive massive weather fronts, storms, and massive cyclones. . They also detected a clear shift between the hottest region of the exoplanet and the point on the planet closest to the star, as well as variations in the chemical composition of the exoplanet’s atmosphere (measured using spectroscopy).

The research team reached these conclusions by using computational models that help explain observed changes in exoplanet atmospheres. “The amazing detail in exoplanet atmospheric simulations allows us to accurately model the weather on superhot planets like WASP-121 b,” said co-postdoctoral researcher at the California Institute of Technology in Pasadena, California. Leader Jack Skinner explained. of this study. “Now we have made significant progress by combining observational constraints and atmospheric simulations to understand the time-varying weather of these planets.”

“This is very exciting result “We are observing weather patterns on exoplanets,” said Quentin Cienciato, one of the team’s principal investigators and a European Space Agency researcher at the Space Telescope Science Institute in Baltimore, Maryland. Understanding the complexity of the atmospheres of exoplanets of other worlds, especially in the search for exoplanets with habitable conditions.

The work is published in arXiv Preprint server.

WASP-121 b is so close to its parent star that its orbital period is only 1.27 days. This closeness means the planet is tidally locked, with the same hemisphere always facing the star, just as the moon always has the same side facing Earth. On the star-facing side of the planet, daytime temperatures approach 3,450 degrees Fahrenheit (2,150 degrees Kelvin).

The team used four sets of Hubble archive observations of WASP-121 b. The complete dataset included observations of his WASP-121 b passing in front of the star (taken in June 2016). WASP-121 b passing behind the star is also known as a secondary solar eclipse (taken in November 2016). and the brightness of WASP-121 b as a function of its phase angle with respect to the star (a change in the amount of light that Earth receives from exoplanets orbiting its parent star, similar to the phase period of the moon). These data were obtained in March 2018 and February 2019, respectively.

“The collected data set represents a significant amount of observation time for a single planet and is currently the only consistent set of such repeated observations,” Changeat said. Information extracted from these observations was used to infer WASP-121 b’s atmospheric chemistry, temperature, and clouds at various points in time. This resulted in exquisite images of the planet changing over time. ”

Hubble’s unique capabilities are also evident in the extensive science program enabled through Cycle 31 observations, which began on December 1st. About two-thirds of Hubble’s time is devoted to imaging research, and the rest to spectroscopic research. , similar to that used for WASP-121, b. For more information on Cycle 31 Science, recent announcements.