{"id":785758,"date":"2024-07-15T10:33:50","date_gmt":"2024-07-15T15:33:50","guid":{"rendered":"https:\/\/spaceweekly.com\/?p=785758"},"modified":"2024-07-15T10:33:50","modified_gmt":"2024-07-15T15:33:50","slug":"nasas-webb-investigates-eternal-sunrises-sunsets-on-distant-world","status":"publish","type":"post","link":"https:\/\/spaceweekly.com\/?p=785758","title":{"rendered":"NASA\u2019s Webb Investigates Eternal Sunrises, Sunsets on Distant World"},"content":{"rendered":"


\n<\/p>\n

\n
\n
\n
\n
\n
\n
6 Min Read<\/div>\n

\n\t\t\t\t\t\t\t\tNASA\u2019s Webb Investigates Eternal Sunrises, Sunsets on Distant World\t\t\t\t\t\t\t<\/h1>\n<\/p>\n<\/div>\n<\/div>\n
<\/div>\n
<\/div>\n
<\/figure>\n<\/p>\n<\/div>\n<\/div>\n<\/div>\n
\n
\n
\n
Artists concept of WASP-39 b (full image below).<\/figcaption><\/div>\n<\/p>\n<\/div>\n<\/figcaption><\/div>\n<\/p>\n<\/div>\n<\/div>\n

Near-infrared spectral analysis of terminator confirms differences in morning and evening atmosphere<\/em><\/p>\n

Researchers using NASA\u2019s 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\u2014one side of the planet is always exposed to its star, while the other is always shrouded in darkness.<\/p>\n

Using Webb\u2019s 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.<\/p>\n

Image A: Artist Concept WASP-39 b<\/h2>\n
\n
\n
\n
\"Illustration<\/figure>
\n
This artist\u2019s concept shows what the exoplanet WASP-39 b could look like based on indirect transit observations from NASA\u2019s James Webb Space Telescope as well as other space- and ground-based telescopes. Data collected by Webb\u2019s NIRSpec (Near-Infrared Spectrograph) show variations between the eternal morning and evening atmosphere of the planet.<\/div>\n<\/figcaption><\/div>\n<\/div>\n<\/div>\n

Astronomers analyzed the 2- to 5-micron transmission spectrum of WASP-39 b, a technique that studies the exoplanet\u2019s terminator, the boundary that separates the planet\u2019s dayside and nightside. A transmission spectrum is made by comparing starlight filtered through a planet\u2019s 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\u2019s atmosphere.<\/p>\n

\u201cWASP-39 b has become a sort of benchmark planet in studying the atmosphere of exoplanets with Webb,\u201d said N\u00e9stor Espinoza, an exoplanet researcher at the Space Telescope Science Institute and lead author on the study. \u201cIt has an inflated, puffy atmosphere, so the signal coming from starlight filtered through the planet\u2019s atmosphere is quite strong.\u201d<\/p>\n

Previously published Webb spectra of WASP-39b\u2019s atmosphere, which revealed the presence of carbon dioxide, sulfur dioxide, water vapor, and sodium, represent the entire day\/night boundary \u2013 there was no detailed attempt to differentiate between one side and the other.<\/p>\n

Now, the new analysis builds two different spectra from the terminator region, essentially splitting the day\/night boundary into two semicircles, one from the evening, and the other from the morning. Data reveals the evening as significantly hotter, a searing 1,450 degrees Fahrenheit (800 degrees Celsius), and the morning a relatively cooler 1,150 degrees Fahrenheit (600 degrees Celsius).<\/p>\n

Image B: Transmission Spectra<\/h2>\n
\n
\n
\n
\"\"<\/figure>\n<\/div>\n<\/div>\n<\/div>\n

\u201cIt\u2019s really stunning that we are able to parse this small difference out, and it\u2019s only possible due Webb\u2019s sensitivity across near-infrared wavelengths and its extremely stable photometric sensors,\u201d said Espinoza. \u201cAny tiny movement in the instrument or with the observatory while collecting data would have severely limited our ability to make this detection. It must be extraordinarily precise, and Webb is just that.\u201d<\/p>\n

Extensive modeling of the data obtained also allows researchers to investigate the structure of WASP-39 b\u2019s atmosphere, the cloud cover, and why the evening is hotter. While future work by the team will study how the cloud cover may affect temperature, and vice versa, astronomers confirmed gas circulation around the planet as the main culprit of the temperature difference on WASP-39 b.<\/p>\n

On a highly irradiated exoplanet like WASP-39 b that orbits relatively close to its star, researchers generally expect the gas to be moving as the planet rotates around its star: Hotter gas from the dayside should move through the evening to the nightside via a powerful equatorial jet stream. Since the temperature difference is so extreme, the air pressure difference would also be significant, which in turn would cause high wind speeds.<\/p>\n

Image C: Transit Light Curve<\/h2>\n
\n
\n
\n
\"\"<\/figure>\n<\/div>\n<\/div>\n<\/div>\n

Using General Circulation Models, 3-dimensional models similar to the ones used to predict weather patterns on Earth, researchers found that on WASP-39 b the prevailing winds are likely moving from the night side across the morning terminator, around the dayside, across the evening terminator and then around the nightside. As a result, the morning side of the terminator is cooler than the evening side. In other words, the morning side gets slammed with winds of air that have been cooled on the nightside, while the evening is hit by winds of air heated on the dayside. Research suggests the wind speeds on WASP-39 b can reach thousands of miles an hour!<\/p>\n

\u201cThis analysis is also particularly interesting because you\u2019re getting 3D information on the planet that you weren\u2019t getting before,\u201d added Espinoza. \u201cBecause we can tell that the evening edge is hotter, that means it\u2019s a little puffier. So, theoretically, there is a small swell at the terminator approaching the nightside of the planet.\u201d<\/p>\n

The team\u2019s results have been published in Nature<\/em>.<\/p>\n

The researchers will now look to use the same method of analysis to study atmospheric differences of other tidally locked hot Jupiters, as part of \u00a0Webb Cycle 2 General Observers Program 3969.<\/p>\n

WASP-39 b was among the first targets analyzed by Webb as it began regular science operations in 2022. The data in this study was collected under Early Release Science program 1366, designed to help scientists quickly learn how to use the telescope\u2019s instruments and realize its full science potential.<\/p>\n

The James Webb Space Telescope is the world\u2019s premier space science observatory. Webb is solving mysteries in our solar system, looking beyond to distant worlds around other stars, and probing the mysterious structures and origins of our universe and our place in it. Webb is an international program led by NASA with its partners, ESA (European Space Agency) and CSA (Canadian Space Agency).<\/em><\/p>\n

Downloads<\/h2>\n

Right click any image to save it or open a larger version<\/strong> in a new tab\/window via the browser\u2019s popup menu.<\/p>\n

View\/Download all image products at all resolutions <\/strong>for this article from the Space Telescope Science Institute.<\/p>\n

The research results have been published in Nature<\/em>.<\/strong><\/p>\n<\/p>\n

Media Contacts<\/h2>\n

Rob Gutro<\/strong> \u2013 rob.gutro@nasa.gov
NASA\u2019s Goddard Space Flight Center, Greenbelt, Md.<\/p>\n

Hannah Braun<\/strong> hbraun@stsci.edu Christine Pulliam<\/strong> \u2013 cpulliam@stsci.edu
Space Telescope Science Institute, Baltimore, Md.<\/p>\n<\/p>\n