WASP-43b has cloudy nights and clear days, with equatorial winds blowing around the Earth at 8,050 km (5,000 mph).
This artist's concept shows what the WASP-43b would be like. Image credit: NASA/ESA/CSA/Ralf Crawford, STScI.
WASP-43b is a gaseous exoplanet about the same size as Jupiter but twice its mass.
This otherworld is located approximately 260 light years away in the constellation Sextant.
WASP-43b is so close to its host star, the orange dwarf WASP-43, that it completes its orbit in just 19.5 hours.
It is also locked by gravity, so one hemisphere remains facing the star.
The night side does not receive direct radiation from the stars, but strong easterly winds carry heat from the day side.
Since its discovery in 2011, WASP-43b has been observed by numerous telescopes, including the NASA/ESA Hubble Space Telescope and NASA's now-retired Spitzer Space Telescope.
“With Hubble, we could clearly see that there was water vapor on the day side. Both Hubble and Spitzer suggested that there might be clouds on the night side,” said the astronomer at the Bay Area Environmental Research Institute. Dr. Taylor Bell said.
“But we needed more precise measurements from Webb to actually start mapping temperatures, cloud cover, winds, and more detailed atmospheric composition around the globe.”
WASP-43b is too small and faint to be seen directly with a telescope, and its close orbit and short orbital period make it ideal for phase curve spectroscopy, a technique that measures minute changes in the brightness of star-planet systems. is. Planets orbit around stars.
The brightness data captured by Webb can be used to calculate the planet's temperature, since the amount of mid-infrared radiation emitted by an object is highly dependent on its temperature.
Dr. Bell and colleagues used the following in their research: Web's mid-infrared device (MIRI) measures light from the WASP-43 system every 10 seconds over 24 hours.
“By looking at the entire orbit, we were able to calculate the temperature of different sides of the planet as it rotates into view,” Bell explained. “From there, we were able to create a rough map of global temperatures.”
Measurements show average daytime temperatures near 1,250 degrees Celsius (2,300 degrees Fahrenheit), hot enough to forge iron. On the other hand, the night side is much cooler at 600 degrees Celsius (1,100 degrees Fahrenheit).
This data can also help identify the hottest spots (hotspots) on the planet. The hotspot is located slightly east of the point where it receives the most radiation from the star, the point where the star is highest in the planet's sky. This change is caused by supersonic winds that move the heated air eastward.
“The fact that we can map temperature in this way is real evidence of the sensitivity and stability of the web,” said astronomer Dr Michael Roman from the University of Leicester.
To interpret the map, astronomers used complex 3D atmospheric models like those used to understand weather and climate on Earth.
Analysis revealed that the night side is probably covered with a thick, high layer of clouds, which prevents some infrared radiation from escaping into space.
As a result, the night view is very hot, but looks dimmer and cooler than without clouds.
The broad spectrum of mid-infrared light captured by Webb also made it possible to measure the amount of water vapor and methane around the Earth.
Dr Joanna Barstow, an astronomer at the Open University, said: “Webb has given us the opportunity to understand exactly what molecules we are looking at and to put limits on their abundance.” Ta.
The spectra show clear signs of water vapor on the dayside as well as the nightside of the Earth, providing additional information about cloud thickness and cloud height in the atmosphere.
Surprisingly, the data also show a distinct lack of methane anywhere in the atmosphere. During the day it's too hot for methane to be present (most of the carbon should be in the form of carbon monoxide), but on the cooler night side methane should be stable and detectable.
“The fact that we don't see methane indicates that WASP-43b's wind speeds must reach around 5,000 miles per hour,” Dr. Barstow said.
“If the wind moves the gas from the day side to the night side and back to the day side fast enough, the expected chemical reaction will be sufficient to produce detectable amounts of methane on the night side. there is no time.”
“Webb's new observational capabilities have revealed WASP-43b in unprecedented detail,” said Dr. Laura Kreidberg, director of the Max Planck Institute for Astronomy.
“What we are witnessing is a complex and inhospitable world, with fierce winds, drastic temperature changes, and patchy clouds, perhaps made of rock spray.”
“WASP-43b is a reminder of the vast range of climates that can occur on exoplanets and that Earth is special in many ways.”
of result It was published in the magazine natural astronomy.
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TJ Bell other. Night clouds and unbalanced chemistry on hot Jupiter WASP-43b. Nat Astron, published online on February 22, 2024. doi: 10.1038/s41550-024-02230-x
Source: www.sci.news
