Astronomers sniff out pungent exoplanet

An exoplanet located a mere 64 light-years away, with a reputation for its extreme weather conditions, is now known for something else — a distinctive rotten-egg odor.

A team of astronomers used data from the James Webb Space Telescope to uncover a surprising aspect of the Jupiter-sized gas giant HD 189733 b — it has an atmosphere rich in hydrogen sulfide.

The detailed study, which was published in Nature, provides researchers with insights into the composition of exoplanetary atmospheres. It was led by Guangwei Fu of Johns Hopkins University and includes ASU co-authors Luis Welbanks , Presidential Postdoctoral Fellow and 51 Pegasi b Fellow, and Michael Line , associate professor, both of the School of Earth and Space Exploration

HD 189733 b is a giant — literally and figuratively — in the field. It is one of the first hot Jupiters ever discovered and has been the subject of constant research for the last two decades. Having the opportunity to finally study it with our best space telescope yet is exhilarating.

— Luis Welbanks, ASU School of Earth and Space Exploration Presidential Postdoctoral Fellow

The planet, which is unlike anything in our solar system, continues to fascinate scientists. It has an orbit lasting only about two Earth days, and temperatures soaring to 1,700 degrees Fahrenheit. The team studied this canonical hot Jupiter with JWST and found that it has an atmosphere predominantly made of hydrogen sulfide, a molecule that not only gives off a stench but also offers scientists new clues about how sulfur, a building block of planets, might influence the insides and atmospheres of gas worlds beyond the solar system.