NASA's Webb investigates eternal sunrises, sunsets on distant world

July 15, 2024
Source:
NASA/Goddard Space Flight Center

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Researchers using NASA's James Webb Space Telescope have finally confirmed what models have previously predicted: An exoplanet has differences between its eternal morning and eternal evening atmosphere. WASP-39 b, a giant planet with a diameter 1.3 times greater than Jupiter, but similar mass to Saturn that orbits a star about 700 light-years away from Earth, is tidally locked to its parent star. This means it has a constant dayside and a constant nightside -- one side of the planet is always exposed to its star, while the other is always shrouded in darkness.

Using Webb's NIRSpec (Near-Infrared Spectrograph), astronomers confirmed a temperature difference between the eternal morning and eternal evening on WASP-39 b, with the evening appearing hotter by roughly 300 Fahrenheit degrees (about 200 Celsius degrees). They also found evidence for different cloud cover, with the forever morning portion of the planet being likely cloudier than the evening.

Astronomers analyzed the 2- to 5-micron transmission spectrum of WASP-39 b, a technique that studies the exoplanet's terminator, the boundary that separates the planet's dayside and nightside. A transmission spectrum is made by comparing starlight filtered through a planet's atmosphere as it moves in front of the star, to the unfiltered starlight detected when the planet is beside the star. When making that comparison, researchers can get information about the temperature, composition, and other properties of the planet's atmosphere.

"WASP-39 b has become a sort of benchmark planet in studying the atmosphere of exoplanets with Webb," said Néstor Espinoza, an exoplanet researcher at the Space Telescope Science Institute and lead author on the study. "It has an inflated, puffy atmosphere, so the signal coming from starlight filtered through the planet's atmosphere is quite strong."

More:
https://www.sciencedaily.com/releases/2024/07/240715135814.htm







WASP-39b Wikipedia:

WASP-39b, officially named Bocaprins, is a "hot Jupiter" extrasolar planet discovered in February 2011[3] by the WASP project, notable for containing a substantial amount of water in its atmosphere.[1][4][5] In addition WASP-39b was the first exoplanet found to contain carbon dioxide in its atmosphere,[6][7] and likewise for sulfur dioxide.

WASP-39b is in the constellation Virgo, and is about 700 light-years from Earth.[1] As part of the NameExoWorlds campaigns at the 100th anniversary of the IAU, the planet was named Bocaprins, after the beach Boca Prins [de; es] in the Arikok National Park of Aruba.

More:
https://en.wikipedia.org/wiki/WASP-39b