Produced by: Tarun Mishra
Researchers have confirmed differences in the atmosphere between eternal morning and evening on WASP-39 b, a gas giant exoplanet orbiting a G-type star located 700 light-years away from Earth.
WASP-39 b, first discovered in 2011, has a mass similar to Saturn and orbits its star in 4.1 days. It is tidally locked, with one side constantly facing its star and the other in perpetual darkness.
In July 2022, NASA's James Webb Space Telescope, renowned for its capabilities, observed WASP-39 b, becoming the first to study this exoplanet in detail.
Using Webb's NIRSpec (Near-Infrared Spectrograph), astronomers detected a temperature variance between the eternal morning and evening sides of WASP-39 b. Evening temperatures were approximately 200 degrees Celsius hotter than morning temperatures.
Researchers also noted differences in cloud cover, with the eternal morning side appearing cloudier compared to the evening side of the exoplanet.
Néstor Espinoza, lead author and exoplanet researcher at the Space Telescope Science Institute, highlighted WASP-39 b's significance as a benchmark for studying exoplanet atmospheres with Webb.
Previous studies with Webb had identified carbon dioxide, sulphur dioxide, water vapour, and sodium in WASP-39 b's atmosphere, with the new study focusing on delineating differences between day and night sides.
Published in Nature, the study titled "Inhomogeneous Terminators on the Exoplanet WASP-39 b" detailed the precise temperature variations across the planet's terminator region.
Espinoza emphasized Webb's unparalleled sensitivity and stability in near-infrared wavelengths, critical for distinguishing subtle atmospheric differences on distant exoplanets like WASP-39 b.