Astrophysicists have identified a comet-like tail of gas extending approximately 563,000 kilometers from the exoplanet WASP-69 b. This hot Jupiter, located 160 light-years from Earth, is undergoing significant atmospheric loss due to intense radiation from its host star. The findings, published in The Astrophysical Journal, were led by Dakotah Tyler from the University of California, Los Angeles (UCLA).
WASP-69 b completes a revolution around its star in just 3.9 days and is losing about 200,000 tons of gas per second, primarily hydrogen and helium. This atmospheric loss is driven by a process known as photoevaporation, where stellar radiation heats the outer atmosphere, allowing gases to escape.
The stellar wind, a continuous stream of charged particles from the star, shapes the escaping gases into a tail, which is at least seven times longer than the planet itself. Tyler noted that strong stellar winds can influence the gas outflow, creating structured forms similar to a windsock.
Despite the significant gas loss, WASP-69 b is not at risk of losing its entire atmosphere. Over its estimated 7 billion-year lifespan, it has lost an equivalent mass of about seven Earths. This gradual loss enables scientists to observe atmospheric changes in real time, enhancing understanding of planetary evolution and their interactions with stars.
As research on WASP-69 b continues, scientists aim to learn more about how such phenomena occur across various exoplanets and their stellar environments.