A little over two decades since the first confirmation of an exoplanet, astronomers have made incredible progress. Using WASP-18b as a test case, they presented a novel 3D mapping approach. This gas giant is located approximately 400 light years away from our planet. Due to its harsh conditions, scientists have named it an “ultra-hot Jupiter.” WASP-18b is a remarkable exoplanet, roughly ten times the mass of Jupiter. It orbits its host star at an exceptionally fast period of only 23 hours, leading the exoplanet’s surface temperatures to reach upwards of 5,000 degrees Fahrenheit.
That pioneering effort was co-led by Megan Wiener Mansfield, assistant professor of astronomy at the University of Maryland. Using NASA’s James Webb Space Telescope (JWST), scientists conducted the first three-dimensional map of WASP-18b’s atmosphere. This pioneering work revealed unique temperature layers at various elevations. This new and creative approach to our understanding constitutes a big step forward in the study of WASP-18b. It’s a huge precedent for studying other hot Jupiters across the universe.
The Extreme Environment of WASP-18b
WASP-18b’s environment of extreme heat and pressure is unlike anything found in our solar system. Record-breaking heat is hitting every corner of the United States. In just one corner of its atmosphere, the heat is so extreme that it apparently destroys water vapor. While this phenomenon is consistent with theoretical predictions, the fact that they were able to observe it directly has the potential to be a crowning accomplishment for researchers.
“We think that’s evidence that the planet is so hot in this region that it’s starting to break down the water,” – Ryan Challener
Today, WASP-18b orbits its star in under a day. It’s this rapid revolution that makes it quite literally hot. Such close proximity to its stellar host creates conditions that are inhospitable for life as we know it. These groundbreaking revelations that different temperature zones persist within its atmosphere unlock important clues about the planet’s atmospheric dynamics and structure.
Advancements in Mapping Exoplanets
The creative new 3D mapping strategy used for WASP-18b is called spectroscopic eclipse mapping. Interferometry now allows scientists to build very fine atmospheric profiles by looking at light in different wavelengths. This approach is a clear advancement over prior two-dimensional mappings that depended on only one wavelength.
“If you build a map at a wavelength that water absorbs, you’ll see the water deck in the atmosphere, whereas a wavelength that water does not absorb will probe deeper,” – Ryan Challener
This new dual-wavelength approach gives researchers the power to detect and identify changes in the atmosphere. They accomplish this as various regions of the exoplanet surface become visible as it completes an orbit. By detecting these subtle changes, scientists can build better models of exoplanetary atmospheres.
“You’re looking for changes in tiny portions of the planet as they disappear and reappear into view,” – Ryan Challener
Their hard work paid off and allowed the team to produce a super high-resolution temperature map of WASP-18b. This significant accomplishment will help advance the next generation of research on similar exoplanets.
Implications for Future Research
Indeed, the implications of this research go far beyond WASP-18b. Potentially, this new mapping approach could transform how astronomers investigate and characterize exoplanets in other systems. As Ryan Challener noted, this improvement paves the way for studying several dozen other planets we can see with the JWST.
“This new technique is going to be applicable to many, many other planets that we can observe with the James Webb Space Telescope,” – Ryan Challener
The scientists increase the spatial resolution and detail the unique atmospheric characteristics. Now, this lets them study exoplanets as a statistical population rather than individual outlier cases. This shift in perspective could lead to breakthroughs in understanding planetary formation and the potential for habitability outside our solar system.
“With this telescope and this new technique, we can start to understand exoplanets along the same lines as our solar system neighbors,” – Ryan Challener