by The James Webb Space Telescope (JWST) has produced a weather report for a distant planet.
The powerful space telescope forecasts extreme wind speeds, blisteringly hot temperatures and blankets of rock clouds for the earth, named Wasp-43b. So, the extrasolar planet, or “exoplanet,” shows how strange alien planets outside the solar system can be.
WASP-43b orbits a star located approximately 283 light years from Earth; it sits so close to its star, in fact, that it completes an orbit in just about 19 Earth hours. This proximity, which is about 1.3 million miles (2.1 million kilometers), means that the planet, with a mass about 1.8 times that of Jupiter and a width 0.9 times that of the gas giant, is tidally locked to its star, WASP -43.
As such, one side of WASP-43b – the day side – is permanently facing the star and is constantly bombarded by radiation, raising planetary temperatures to around 2,300 degrees Fahrenheit (1,250 degrees Celsius). That’s hot enough to melt lead. The other side of the planet – the night side – permanently faces out into space, causing temperatures to drop to a fairly cold 1,110 degrees Fahrenheit (600 degrees Celsius). These qualities mean that WASP-43b is classified as a “hot Jupiter” planet.
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The JWST Transiting Exoplanet Early Release Science (JTEC-ERS) team was able to use the telescope’s Mid-Infrared Instrument (MIRI) to classify WASP-43b’s climate and the type of weather it experiences on its day and night sides.
“With JWST’s new observing power, WASP-43b has been revealed in unprecedented detail,” team member Laura Kreidberg, Director of the Max Planck Institute for Astronomy (MPIA), said in a statement. “We see a complex, inhospitable world, with furious winds, huge temperature changes and erratic clouds made of rock droplets.
“WASP-43b is a reminder of the wide range of climates possible on exoplanets and the many ways in which Earth is special.”
WASP-43b was discovered in 2011 due to a dip in the light that scientists saw displayed by WASP-43. This fall occurred when the planet crossed between the face of the star and the Earth, from our perspective. During the transit, scientists also saw that the infrared light emitted by the planet in response to the light of different stars.
The main result of the JWST investigation of WASP-43b was thanks to this variation of infrared light, observed between the day and night side of the exoplanet as it orbits its star. The variations, in particular, helped scientists build a map showing how temperatures are distributed across the entire hot Jupiter.
Ultimately, the team found that the temperature difference between the day and night sides of WASP-43b is too large to be seen in an atmosphere without cloud cover. However, any clouds that may be above WASP-43b’s surface are unlikely to be water-based like those that cover Earth. They wouldn’t even be ammonia clouds like the ones we see around Jupiter. WASP-43b is too hot for either. Rather, the clouds of this world could be made of it rock.
Evaporated material, such as rock, is carried from the day side to the night side of WASP-43b by powerful winds that reach speeds of 5,600 miles per hour (9,000 kilometers per hour). That’s three and a half times as fast as the top speed of a jet fighter here on Earth. Then, once on the night side of the planet, scientists believe this material cools and condenses. This means that the thick cloud cover on the night side of WASP-43b is likely to consist of droplets of liquid rock that evaporated during the day of the planet. To that end, the researchers found that the day of WASP-43b appears to be cloudless.
To determine the composition of WASP-43b’s atmosphere, the team split the observed infrared light into separate wavelengths, creating what is called a “spectrum.” Because chemicals and elements absorb and emit light at characteristic wavelengths, they leave behind “fingerprints” in such spectra.
“With Hubble, we could clearly see that there is water vapor on the day side. Hubble and Spitzer suggested that there could be clouds on the night side,” said Taylor Bell, team leader and scientist at NASA’s Ames Research Center. in the statement. “But we needed more accurate measurements from JWST to really start mapping the temperature, cloud cover, winds and composition of the atmosphere in more detail all the way around the planet.”
The JWST investigation not only determined that water vapor was found throughout WASP-43b on both its hot and cold sides, but also allowed scientists to observe the absence of methane in the planet’s atmosphere. Hot Jupiters are usually expected to produce water and methane on their nights through reactions between hydrogen and carbon monoxide.
The team thinks that WASP-43b lacks methane because its raging winds move these reactive molecules through the night side of the planet too quickly for the molecules to react with anything and create methane in detectable amounts. Any small amount of methane formed would likely mix with other gases and be quickly transported to the planet’s surface, where intense heat destroys it.
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The JWST is not done with WASP-43b yet. A separate team is using the $10 billion telescope’s Near-Infrared Spectrometer (NIRSpec) instrument to continue studying the planet.
Not only should this improve the MIRI temperature map, but these observations should also yield gaseous carbon monoxide in the atmosphere of WASP-43b, providing a better overall picture of the chemical composition of this vast world.
The results of WASP-43b were published on April 30 in the journal Nature Astronomy.
