Researchers using NASA’s James Webb Space Telescope have found evidence of quartz nanocrystals in high-altitude clouds of WASP-17 b, a hot Jupiter exoplanet 1,300 light-years from Earth. The unique discovery made by MIRI (Webb’s Mid-Infrared Instrument) is the first time that silica particles (SiO) ₂ ) was observed in the atmosphere of an exoplanet.

Quartz crystals are only 10 nanometers in diameter, so small that 10,000 of them could fit side by side on a human hair. Their sizes and pure silica compositions are described in the publication “JWST-TST DREAMS: Quartz Clouds in the Atmosphere of WASP-17b.” Astrophysics Journal Letters .

“The Hubble data actually played a key role in constraining the size of these particles. We only know silicon dioxide exists from Webb’s MIRI data, but we needed visible and near-infrared observations from Hubble to understand how large the crystals are,” said co-author Nicole Lewis. , assistant professor of astronomy in the College of Arts and Sciences, member of the Carl Sagan Institute, and director of the Webb Guaranteed Time Observation (GTO) program, designed to create a three-dimensional image. View of Jupiter’s hot atmosphere.

Webb observed the WASP-17 system for nearly 10 hours and collected more than 1,275 measurements of the brightness of 5-12 micron infrared light as the planet passed by its star. By subtracting the brightness of individual wavelengths of light reaching the telescope when the planet was in front of the star from the brightness of the individual star, the research team was able to calculate the amount of each wavelength blocked by the planet’s atmosphere.

What was found was an unexpected “bulge” of 8.6 microns; This is best explained by the fact that the clouds are composed of quartz rather than other possible high-temperature aerosols such as magnesium silicates or aluminum oxide. Webb’s unique ability to measure the extremely subtle effects of these crystals on starlight—and from a distance of more than 7 million billion miles—is providing important information about the composition of exoplanet atmospheres and new understanding of their weather conditions.

The results of the paper’s authors, who are part of the JWST telescope research team and include researchers from NASA Ames Research Center and NASA Goddard Space Flight Center, provide new insight into our understanding of how exoplanet clouds form and evolve. The researchers found that pure silica, the building blocks, is required to form the larger silicate grains found on brown dwarfs and cooler exoplanets, rather than the magnesium-rich silicates such as olivine and pyroxene seen on other exoplanets.

With a volume seven times that of Jupiter and less than half the mass of Jupiter, WASP-17 b is one of the largest and “pudtest” exoplanets known. This, together with a short orbital period of 3.7 Earth days, makes the planet ideal for transmission spectroscopy: a technique that involves revealing the compositional properties of a planet’s atmosphere by measuring its filtering and scattering effects on starlight.

Quartz crystals found in WASP-17 b’s clouds are not dragged from the rocky surface, unlike mineral particles found in clouds on Earth. Instead, they occur in the atmosphere itself.

“WASP-17 b is extremely hot (about 2,700 degrees Fahrenheit), and the pressure at which quartz crystals form high in the atmosphere is only one-thousandth of the pressure we experience at the Earth’s surface. “Under these conditions, solid crystals can form directly from gases without first passing through the liquid phase,” said first author David Grant from the University of Bristol.

“It’s difficult to determine exactly how much quartz is there and how widespread the clouds are, but the team aims to do just that by combining these WASP-17b observations with other observations of the system from JWST,” Lewis said.

WASP-17 b is one of three planets targeted by the Deep Exploration of Exoplanet Atmospheres Using the JWST Telescope Multi-Instrument Spectroscopy (DREAMS) team of scientists, which is designed to collect the complete set of observations of one representative of each major class of exoplanets. : hot Jupiter, hot Neptune and a temperate rocky planet. MIRI observations of hot Jupiter WASP-17 b were carried out as part of the GTO 1353 program.