There’s a fascinating exoplanet 400 light-years away that’s so intriguing that astronomers have been researching it since its discovery in 2009. WASP-18 b takes only 23 hours to complete one orbit around its star (which is slightly larger than our Sun). Nothing like it exists in our solar system. WASP-18 b, an extrasolar planet ten times the mass of Jupiter, has been detected by NASA’s Hubble, Chandra, TESS, and Spitzer satellite telescopes as well as ground-based observatories. Astronomers are already looking via NASA’s James Webb Space Telescope, and the ”firsts” keep arriving.

The discovery: Scientists discovered water vapor in extrasolar planet’s (WASP-18 b) atmosphere and created a temperature map of the planet as it disappeared behind and resurfaced from its star. This is referred to as a secondary eclipse. Scientists can read the combined light from the star and the planet, then refine the measurements from the star alone when the planet travels behind it.

The same side of WASP-18 b, known as the dayside, always faces the star, just as the same side of the Moon always faces Earth. The temperature, or brightness, map depicts a large temperature shift – up to 1,000 degrees – from the warmest point facing the star to the terminator, where the day and night sides of the tidally-locked planet meet in perpetual twilight.

‘‘JWST is giving us the sensitivity to make much more detailed maps of extrasolar planets like WASP-18 b than ever before. This is the first time a planet has been mapped with JWST, and it’s really exciting to see that some of what our models predicted, such as a sharp drop in temperature away from the point on the planet directly facing the star, is actually seen in the data!’’ said Megan Mansfield, a Sagan Fellow at the University of Arizona, and one of the authors of the paper describing the results.

Temperature gradients were mapped over the planet’s dayside by the researchers. Given how much cooler the globe is at the terminator, something is most certainly preventing winds from efficiently dispersing heat to the night side. But what is influencing the winds remains a mystery.

‘‘The brightness map of WASP-18 b shows a lack of east-west winds that is best matched by models with atmospheric drag. One possible explanation is that this planet has a strong magnetic field, which would be an exciting discovery!’’ said co-author Ryan Challener, of the University of Michigan.

According to one interpretation of the eclipse map, magnetic factors cause winds to blow from the planet’s equator up over the North pole and down over the South pole, rather than east-west as we would expect.

Temperature fluctuations were measured at various elevations of the gas giant planet’s atmospheric layers. Temperatures rose with altitude and varied by hundreds of degrees.

Despite tremendous temperatures of over 5,000 degrees Fahrenheit (2,700 degrees Celsius), the spectrum of the planet’s atmosphere indicates many small but accurately measured water structures. It’s so hot that most water molecules would be ripped apart, thus recognizing its presence speaks to Webb’s amazing sensitivity to detect leftover water. The levels of water vapor detected in the atmosphere of WASP-18 b show that it exists at varied heights.

WASP-18 b Spectrum
Credit: NASA/JPL-Caltech (R. Hurt/IPAC)

‘‘It was a great feeling to look at WASP-18 b’s JWST spectrum for the first time and see the subtle but precisely measured signature of water,’’ said Louis-Philippe Coulombe, a graduate student at the University of Montreal and lead author of the WASP-18 b paper. ‘‘Using such measurements, we will be able to detect such molecules for a wide range of planets in the years to come!’’

Extrasolar planet WASP-18 b was observed for around six hours by researchers using one of Webb’s instruments, the Near-Infrared Imager and Slitless Spectrograph (NIRISS), which was donated by the Canadian Space Agency.

‘‘Because the water features in this spectrum are so subtle, they were difficult to identify in previous observations. That made it really exciting to finally see water features with these JWST observations,’’ said Anjali Piette, a postdoctoral fellow at the Carnegie Institution for Science and one of the authors of the new research.

The discoverers are as follows: Through the Transiting Exoplanet Community Early Release Science Program, which is coordinated by Natalie Batalha, an astronomer at the University of California, Santa Cruz, who helped coordinate the new research, more than 100 scientists from across the world are working on early science from Webb. Young scientists like Coulombe, Challener, Piette, and Mansfield are doing a lot of innovative work.

WASP-18 b’s proximity to its star and us, as well as its massive mass, contributed to its appeal to scientists. WASP-18 b is one of the largest worlds whose atmospheres we can study. We’d like to know how such planets arise and end up where they are. This, too, has some early Webb responses.

‘‘By analyzing WASP-18b’s spectrum, we not only learn about the various molecules that can be found in its atmosphere but also about the way it formed. We find from our observations that WASP-18 b’s composition is very similar to that of its star, meaning it most likely formed from the leftover gas that was present just after the star was born,’’ Coulombe said. ‘‘Those results are very valuable to get a clear picture of how strange planets like WASP-18 b, which have no counterpart in our solar system, come to exist.’’

WASP-18_b Eclipse
Credit: NASA/JPL-Caltech (R. Hurt/IPAC)

NASA’s James Webb Space Telescope (JWST) has detected silicate cloud features in the atmosphere of a distant exoplanet called VHS 1256 b, which is located about 40 light-years away from us. VHS 1256 b is a planetary-mass object that orbits not one but two stars over 10,000 years. The atmosphere of this exoplanet is very dynamic, constantly mixing and moving during its 22-hour day. This makes it the most variable planet-size object ever discovered.

The research team, led by Brittany Miles of the University of Arizona, used data from JWST. This data help them to identify water, methane, carbon monoxide, and carbon dioxide in the planet’s atmosphere. This is the largest number of molecules ever discovered at once on an extrasolar planet. They also detected both larger and smaller silicate dust grains in the planet’s atmosphere. These findings provide insights into the planet’s weather and atmospheric dynamics.

Exoplanet (VHS 1256 b)
Credits: Illustration: NASA, ESA, CSA, Joseph Olmsted (STScI)

But first, find out

What is VHS 1256 b?

VHS 1256 b is an exoplanet located about 40 light-years away from Earth. This planet orbits two stars and is one of the most variable planetary-mass objects ever observed. Its atmosphere is constantly changing, and it has swirling, gritty silicate clouds that are so surprising that they create significant brightness changes. Using the JSWT, researchers were able to detect a range of molecules in VHS 1256 b’s atmosphere. Molecules include water, methane, carbon monoxide, and carbon dioxide.

Professor A Biller of the University of Edinburgh says: There’s a huge return on a very modest amount of telescope time,” She added. “With only a few hours of observations, we have what feels like the unending potential for additional discoveries.”

Compared to other brown dwarfs with greater mass, VHS 1256 b exhibits lower gravity, allowing its silicate clouds to persist at higher altitudes where they can be observed. Moreover, the planet is relatively youthful, originating 150 million years ago. Over billions of years, it will continue to alter and cool. Exoplanet has already revealed many amazing facts about their atmosphere and environment. Scientists are still analyzing the data gathered by the James Webb Space Telescope.

A researcher at the University of Edinburgh in Scotland, Beth Biller says: “The finer silicate grains in its atmosphere may be more like tiny particles in smoke”. Moreover, she said: “The larger grains might be more like very hot, very small sand particles.”

Exoplanet Atmosphere
Credits: Image: NASA, ESA, CSA, J. Olmsted (STScI); Science: Brittany Miles (University of Arizona), Sasha Hinkley (University of Exeter), Beth Biller (University of Edinburgh), Andrew Skemer (University of California, Santa Cruz

Now, the question here is

How has JSWT observed this exoplanet?

The researchers used two instruments aboard the James Webb Space Telescope. One of which is called the Near-Infrared Spectrograph (NIRSpec). The second one is the Mid-Infrared Instrument (MIRI), to gather data known as spectra. Because VHS 1256 b orbits at a great distance from its two stars, the researchers were able to observe the planet directly without having to use a technique called a transit, which involves observing the dip in brightness of a star when a planet passes in front of it, or a coronagraph, which blocks the light of the star to reveal fainter objects nearby. This direct observation allowed for a more detailed analysis of the exoplanet’s atmosphere and the molecules presents within it.

Now come to the point,

What is the significance of this observation?

The observation of VHS 1256 b has provided scientists with a wealth of data about the planet’s atmosphere. Particularly about the composition and behavior of its clouds. This is significant because the study of exoplanet atmospheres is a key area of research in understanding the origins of our solar system and the possibility of life beyond it. Observing VHS 1256 b has allowed researchers to identify multiple features in the planet’s atmosphere simultaneously. This data will serve as a valuable resource for future modeling efforts.  Moreover, it will help scientists better understand the atmospheric conditions on exoplanets.

A research team led by Brittany Miles of the University of Arizona says: “We’ve identified silicates, but better understanding which grain sizes and shapes match specific types of clouds is going to take a lot of additional work,” He added: “This is not the final word on this planet – it is the beginning of a large-scale modeling effort to fit Webb’s complex data.”

The findings have opened up new avenues for research and highlighted the power of the James Webb Space Telescope in exploring the mysteries of the universe. Andrew Skemer, an Associate Professor at the University of California, Santa Cruz says: “No other telescope has identified so many features at once for a single target,” Moreover, he explains: “We’re seeing a lot of molecules in a single spectrum from Webb that detail the planet’s dynamic cloud and weather systems.”


Published by: Sky Headlines