The Webb Telescope discovers Quartz Nanocrystals in the Skies of WASP-17 b

This artistic depiction offers a glimpse of exoplanet WASP-17 b, also known as Ditsö̀. Located 1,300 light-years away in the Scorpius constellation within the Milky Way, this hot gas giant orbits its star at an incredibly close distance, completing one orbit in just 3.7 Earth-days. WASP-17 b's atmosphere, primarily composed of hydrogen and helium, features unique clouds made of quartz nanocrystals, as revealed by the James Webb Space Telescope's Mid-Infrared Instrument (MIRI). This tidally locked exoplanet exhibits a substantial temperature range, with its nightside being cooler and its dayside experiencing scorching temperatures due to constant exposure to daylight. The central star, WASP-17 (Diwö), belongs to the F-type star category, characterized by its larger size, greater mass, higher temperature, and whiter appearance compared to the Sun. This artist's representation incorporates data from various telescopes, including NASA's Hubble and retired Spitzer space telescopes, though direct imaging of the planet has not yet been accomplished. Credits:NASA, ESA, CSA, Ralf Crawford (STScI)

Oct 16, 2023 -  In a monumental leap forward for exoplanetary research, NASA's James Webb Space Telescope has shattered the boundaries of our knowledge by revealing a groundbreaking discovery about the enigmatic exoplanet WASP-17 b. Situated a mind-boggling 1,300 light-years away from Earth, this gas giant, often referred to as a "hot Jupiter," has been the focus of intense scrutiny by astronomers. Researchers, wielding the remarkable capabilities of the Webb telescope, have uncovered evidence of quartz nanocrystals dwelling within the planet's high-altitude clouds. This remarkable revelation challenges our understanding of exoplanet atmospheres, introducing the possibility of silica (SiO2) particles within these distant skies. The implications of this discovery could transform our comprehension of how exoplanet clouds form and evolve, potentially rewriting the narrative of planetary science.

Detecting Subtle Variations

WASP-17 b, a hot Jupiter exoplanet, is nothing short of a celestial enigma. It boasts a volume over seven times that of our Solar System's largest planet, Jupiter. Its massive size, coupled with an incredibly short orbital period of just 3.7 Earth-days, makes it a unique specimen for the fascinating realm of exoplanetary science. These attributes render WASP-17 b an ideal candidate for a specialized technique known as transmission spectroscopy, which involves measuring the impact of an exoplanet's atmosphere on starlight as it transits its host star.

The James Webb Space Telescope embarked on a meticulous observation campaign, studying the WASP-17 system for nearly ten hours. During this time, it collected a wealth of data, encompassing more than 1,275 brightness measurements of mid-infrared light with wavelengths ranging from 5 to 12 microns.

However, what truly set this observation apart was the startling revelation of an intriguing feature: a distinctive "bump" at 8.6 microns. This peculiar characteristic was entirely inconsistent with prior assumptions about the composition of exoplanet clouds, challenging the prevailing belief that magnesium silicates or other high-temperature aerosols, such as aluminum oxide, comprised their constituents. Instead, this remarkable discovery hints at the possibility of the clouds on WASP-17 b being composed of quartz, a mineral predominantly consisting of SiO2.

This unique feature marks the first known instance of SiO2 in an exoplanet's atmosphere, representing an exciting leap forward in our understanding of exoplanetary environments.

Crystals, Clouds, and Winds

The nature of these quartz crystals found on WASP-17 b sets them apart from the minerals found in Earth's clouds. On our planet, cloud particles originate from the surface and are transported to higher altitudes by atmospheric processes. In the case of WASP-17 b, the crystals are not swept up from a rocky surface, as there is no solid ground to speak of. Instead, they originate directly within the planet's atmosphere.

What makes this possible is the unique environmental conditions of WASP-17 b. With temperatures soaring to a scorching 1,500 degrees Celsius (2,700°F) and atmospheric pressures only around one-thousandth of Earth's surface pressure, solid crystals can form directly from gas, bypassing the liquid phase entirely. Unlike the familiar processes that create cloud droplets on Earth, the clouds of WASP-17 b form through a direct, gas-to-crystal transition.

The identification of these SiO2 crystals not only marks an extraordinary scientific achievement but also offers valuable insights into the planet's composition. Hot Jupiters like WASP-17 b are primarily composed of hydrogen and helium, with traces of other gases such as water vapor and carbon dioxide. However, this discovery hints at the significant role quartz plays in shaping the planet's environment. Neglecting the presence of SiO2 could lead to a substantial underestimation of the overall abundance of oxygen on the exoplanet.

The exact quantity of quartz within the clouds and their extent remains a challenging endeavor. These clouds are likely concentrated along the day/night transition zone, known as the terminator, which is the region explored by the observations. Given that WASP-17 b is tidally locked, with a scorching day side and a cooler night side, the clouds may circulate and migrate at high speeds of thousands of miles per hour. These high-velocity winds could be responsible for the movement of these tiny glassy particles, dispersing them across the exoplanet's atmosphere.

Significance and Implications

The discovery of quartz nanocrystals within the clouds of WASP-17 b carries profound significance for the field of exoplanetary science. Firstly, it expands our knowledge of the exoplanetary composition. The presence of SiO2 in these high-altitude clouds reveals that the inventory of materials on this hot Jupiter is more diverse than initially thought. If we consider the oxygen present only in the gases, such as hydrogen and helium, and neglect the substantial quantities locked up in minerals like quartz, we risk underestimating the total abundance of oxygen on the exoplanet. This discovery sheds light on the complexity of exoplanetary atmospheres, urging researchers to incorporate various materials into their models.

Furthermore, the discovery of quartz nanocrystals is a testament to the remarkable capabilities of the James Webb Space Telescope and the potential for groundbreaking discoveries that lie ahead. Webb's contribution to our understanding of exoplanets is unparalleled, and this revelation underscores the pivotal role it plays in unraveling the mysteries of the cosmos.

The presence of SiO2 also challenges existing models of cloud formation on exoplanets. Prior to this discovery, it was widely believed that magnesium silicates, like olivine and pyroxene, formed the basis of exoplanetary clouds. The identification of quartz suggests that these nanocrystals may serve as the building blocks, or "seeds," for the formation of larger silicate grains. This reevaluation of cloud formation processes is essential for refining our understanding of the evolution of exoplanetary atmospheres.

The James Webb Space Telescope

The James Webb Space Telescope, often heralded as the world's premier space science observatory, has consistently exceeded expectations in its mission to unravel the mysteries of our universe. Webb's far-reaching objectives include scrutinizing our solar system, delving into the realms of distant worlds orbiting other stars, and unraveling the enigmatic structures and origins of the universe. This groundbreaking endeavor is an international collaboration led by NASA, with the essential contributions of the ESA (European Space Agency) and the Canadian Space Agency.

The revelation of quartz nanocrystals in the clouds of WASP-17 b through the James Webb Space Telescope marks a milestone in exoplanetary research. It underscores the incredible potential of advanced observatories to revolutionize our understanding of the universe. This discovery signifies a new chapter in our quest to comprehend the intricate atmospheres of exoplanets and challenges us to refine our models to incorporate the diversity of materials found in these distant worlds.

The existence of SiO2 crystals on WASP-17 b is a testament to the astounding diversity of the cosmos, urging us to expand our horizons and consider the extraordinary possibilities that await us in the universe

Source - NASA

In March 2023, the James Webb Space Telescope's Mid-Infrared Instrument (MIRI) captured a transmission spectrum of hot gas giant exoplanet WASP-17 b. This data unveiled the groundbreaking discovery of quartz (SiO2) within its clouds, a first in exoplanet science. By observing the planet for nearly 10 hours, Webb collected over 1,275 measurements, allowing astronomers to measure how much light was blocked by the planet's atmosphere for each wavelength. The resultant spectrum exhibited a prominent feature around 8.6 microns, attributed to silica particles absorbing starlight. The spectrum also displayed a comparison (dashed yellow line) to illustrate how the transmission spectrum would appear without SiO2 in the planet's atmosphere. Credits: NASA, ESA, CSA, Ralf Crawford (STScI)