Detection of Crystalline Silica in the Atmosphere of Hot Gas Giant WASP-17 b

The conceptual illustration presents what the exoplanet WASP-17 b, also known as Ditsö̀, might resemble. This hot gas giant orbits its star at a mere distance of 0.051 AU, equivalent to approximately 4.75 million miles, and completes an orbit in roughly 3.7 Earth-days. Situated in the Milky Way galaxy within the Scorpius constellation, it lies 1,300 light-years away from Earth. WASP-17 b is characterized by its immense volume, which is over seven times that of Jupiter, while its mass is less than half. These characteristics, coupled with its dense, expansive atmosphere and short orbital period, make it an excellent candidate for observational studies using transmission spectroscopy. Credit: NASA, ESA, CSA, Ralf Crawford (STScI)

Airborne particles of crystalline silica, or quartz “snow,” pervade the atmosphere of the voluminous and extremely hot exoplanet WASP-17 b.

While quartz is a ubiquitous mineral on Earth—found in sandy beaches, architectural materials, and even in timekeeping devices—it rarely garners significant attention. The mineral is also used in the creation of glass and the manufacturing of silicon-based microchips.

The latest findings from NASA’s James Webb Space Telescope have introduced an extraordinary aspect of quartz: the presence of nanoscale quartz crystals in the atmosphere of a hot gas giant exoplanet, small enough that 10,000 could line up across a strand of human hair. These minuscule particles zip through the torrid atmosphere of WASP-17 b at velocities reaching thousands of miles per hour.

Webb’s sophisticated capabilities in measuring the very slight impact of these crystals on the starlight from a staggering distance have furnished crucial data concerning the makeup of exoplanet atmospheres and have provided new perspectives on their meteorological conditions.

A transmission spectrum captured by MIRI, Webb’s Mid-Infrared Instrument, between March 12-13, 2023, discloses the inaugural evidence of quartz crystals present in an exoplanetary atmosphere. This pioneering discovery marks the first time crystalline silica (SiO2) has been identified in such a context. Credit: NASA, ESA, CSA, Ralf Crawford (STScI), David Grant (University of Bristol), Hannah R. Wakeford (University of Bristol), Nikole Lewis (Cornell University)

James Webb Space Telescope Identifies Minute Quartz Particles in Hot Gas Giant Atmosphere

A team of researchers utilizing the James Webb Space Telescope has discovered traces of quartz nanocrystals within the upper clouds of the distant exoplanet WASP-17 b. The groundbreaking observation, made possible by Webb’s Mid-Infrared Instrument (MIRI), signifies the first time crystalline silica has been detected in the atmosphere of an exoplanet.

David Grant from the University of Bristol, the lead author of the study, expressed elation over the unexpected finding. Although the presence of aerosols in the atmosphere of WASP-17 b had been suspected from previous observations by the Hubble Telescope, quartz had not been anticipated.

Silicates, which are rich in silicon and oxygen, constitute the majority of terrestrial and lunar minerals as well as other rocky celestial objects. However, prior to this finding, the types of silicates discovered in the atmospheres of exoplanets and brown dwarfs were predominantly magnesium-rich varieties like olivine and pyroxene, not pure SiO2 or quartz.

The revelation has implications for our understanding of the formation and evolution of exoplanetary clouds. Researchers had initially anticipated the presence of magnesium silicates but instead discovered what appear to be the precursor particles to these larger silicate grains.

Detailed Observations

WASP-17 b’s expansive volume and relatively low mass make it an ideal subject for transmission spectroscopy. Webb monitored the WASP-17 system over a span of nearly 10 hours, accumulating over 1,275 measurements of brightness in mid-infrared wavelengths. This data allowed researchers to calculate the variations in light intensity as the planet transited its star, revealing an unexpected feature at 8.6 microns, consistent with the presence of quartz crystals.

Implications for Planetary Science

The quartz crystals in WASP-17 b’s atmosphere are estimated to be just 10 nanometers in diameter and are not formed from solid surfaces but are created within the atmosphere itself. This information contributes to the broader understanding of the planet’s composition, primarily consisting of hydrogen and helium, and helps in accurately assessing the planet’s overall elemental abundance.

The exact amount of quartz and the extent of its distribution are still undetermined, but the particles likely circulate within the planet’s atmosphere, disintegrating upon reaching its hotter side. High-speed winds could be responsible for this rapid circulation.

WASP-17 b is one of three celestial bodies being studied under the Deep Reconnaissance of Exoplanet Atmospheres using Multi-instrument Spectroscopy (DREAMS) initiative, a part of GTO program 1353.

Reference and Collaboration

The James Webb Space Telescope is a leading space science observatory, resolving enigmas in our solar system and beyond. It is an international endeavor led by NASA, in association with its partners, the European Space Agency and the Canadian Space Agency.

Frequently Asked Questions (FAQs) about James Webb Space Telescope

More about James Webb Space Telescope

• James Webb Space Telescope Official Site
• University of Bristol Research Publications
• NASA’s Ames Research Center Studies on Exoplanet Atmospheres
• Goddard Space Flight Center’s Exoplanet Exploration
• WASP-17 b Overview in the Exoplanet Archive
• Deep Reconnaissance of Exoplanet Atmospheres using Multi-instrument Spectroscopy (DREAMS)
• Transmission Spectroscopy Explained
• Hubble Space Telescope Observations of Exoplanets