In a first, the James Webb Space Telescope has detected a smelly, uncommon atmospheric element on a nearby exoplanet, HD 189733 b, an angry gas giant that sports extreme weather and gives off scorching air. According to a new paper published Wednesday in Nature, this discovery adds new depth to our understanding of the “hot Jupiter” and its atmosphere rich with sulfur.
HD 189733 b; This gas giant orbits about 13 times closer to its star than Mercury orbits the sun, putting it roughly 64 light-years away in the constellation Vulpecula. Due to this close approach, its surface temperature reaches a blistering 1,700 degrees Fahrenheit, enough to melt some rocks into magma. This exoplanet is having a rotation period of two days and, hitherto recorded, rains sideways-blowing molten glass rain, driven by winds that howl at up to 5,000 mph.
The latest findings from JWST have identified trace amounts of hydrogen sulfide in the planet’s atmosphere. This toxic and flammable gas, known for its rotten egg smell, is a significant discovery for scientists. “Hydrogen sulfide is a major molecule that we didn’t know was there,” said Guangwei Fu, an astrophysicist at Johns Hopkins University and the study’s lead author. He explained that while this molecule is present in the atmospheres of Jupiter and Uranus, its detection outside our solar system is rare.
The presence of hydrogen sulfide on HD 189733 b would establish that sulfur is abundant on this extrasolar planet, where it is one of the basic elements to construct more complicated molecules. Fu stressed that although it is unlikely that life could exist in extreme conditions like those on HD 189733 b, the detection of hydrogen sulfide was a matter of great importance for understanding how various types of planets come into existence and their detailed composition.
Advanced instruments on JWST have changed the scene for exoplanet studies, allowing for the identification of a host of chemicals across space: greenhouse gases on moons in our solar system, water around other stars, and carbon going back to very early times. A year ago, the telescope spotted the first dimethyl sulfide of K2-18 b in the atmosphere, an ocean-covered exoplanet, a compound known to be produced by living organisms on Earth.
Though Fu’s team also calculated water, carbon dioxide, and carbon monoxide content of the atmosphere of HD 189733 b—giving the overall understanding of composition—the group ruled out methane, which was previously claimed to exist in huge amounts on the exoplanet. “We had been thinking this planet was too hot to have high concentrations of methane, and now we know that it doesn’t,” Fu noted.
It was also revealed that similar to Jupiter, HD 189733 b was loaded with heavy metal, opening thus the way to unravel how the metallicity of a planet goes with its mass. The less-massive icy giants, like Neptune and Uranus, hold more metals than gas giants like Jupiter and Saturn, pointing at different formation processes.
In the next couple of months, Fu’s team will continue to observe more “hot Jupiters” with JWST and detect more sulfur in those exoplanets. “We want to know how these kinds of planets got there, and understanding their atmospheric composition will help us answer that question, ” said Fu.
The discovery of hydrogen sulfide on HD 189733 b not only enhances our knowledge of this particular exoplanet but also provides valuable insights into the broader field of planetary science. As Fu aptly put it, “Understanding the composition of this and other exoplanets allows us to understand how unique our own solar system is and helps us place our existence in context.”
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