Chasing its tail in the cosmos

University of Waterloo astronomers have discovered massive streams of helium gas trailing and leading an exoplanet, challenging existing ideas about atmospheric loss on giant planets. Using the James Webb Space Telescope, researchers observed the ultra-hot Jupiter WASP-121 b shedding helium in extended tails that stretch across roughly 60 per cent of its orbit. This was unexpected, as planets of this size were thought to retain their atmospheres due to strong gravity.

The findings, published in Nature Communications, suggest atmospheric escape on giant planets may be more complex than previously believed and open the door to further JWST studies of similar exoplanets.