The James Webb Space Telescope discovers its first exoplanet

This illustration reflects the conclusion that the exoplanet LHS 475 b is rocky and almost precisely the same size as Earth. The planet whips around its star in just two days, far faster than any planet in the Solar System.
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This illustration shows the conclusion that the exoplanet LHS 475 b is rocky and about the same size as Earth. The planet orbits its star faster than any planet in the Solar System in just two days. (NASA Illustration)

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LAUREL, Md. — The James Webb Space Telescope can add another space achievement to its list: The space observatory was used for the first time to confirm the existence of an exoplanet.

Known as LHS 475 b, the celestial body outside our solar system is almost the same size as Earth. The rocky world is 41 light-years away in the constellation Octanes.

Previous data collected by NASA’s Transiting Exoplanet Survey Satellite, or TESS, suggested the planet might exist.

A team of researchers led by astronomer Kevin Stevenson and Jacob Lustig-Yaeger, a postdoctoral fellow at the Johns Hopkins University Applied Physics Laboratory in Laurel, Maryland, observed the target using Webb. They watched as the planet passed in front of its star, a dip in starlight called a transit, and watched two transits occur.

“There is no doubt that the planet is there. Webb’s clean data confirms it,” Lustig-Yaeger said.

The discovery of the planet was announced Wednesday at the 241st meeting of the American Astronomical Society in Seattle.

“The fact that it’s also a small, rocky planet is impressive for the observatory,” Stevenson said.

Webb is the only telescope capable of characterizing the atmospheres of Earth-sized exoplanets. The research team used Webb to analyze the planet across multiple wavelengths of light to see if it has an atmosphere. So far, the team has not been able to draw any definitive conclusions, but the telescope’s sensitivity has increased on a number of molecules present.

“There are some terrestrial-type atmospheres that we can rule out,” Lustig-Yaeger said. “It cannot have a thick methane-dominated atmosphere similar to that of Saturn’s moon Titan.”

Astronomers will have another chance in the summer to observe the planet again and make follow-up analyzes of the potential presence of an atmosphere.

Webb’s discoveries also revealed that the planet is several hundreds of degrees warmer than our own. If researchers detect any clouds on LHS 475 b, it could be more like Venus—which is considered Earth’s hotter twin with its carbon dioxide atmosphere.

This graph shows the change in relative brightness of the host star and the planet over three hours.
This graph shows the change in relative brightness of the host star and the planet over three hours. (Image: NASA)

“We are at the forefront of exploring small, rocky exoplanets,” Lustig-Yaeger said. “We’ve almost begun to scratch the surface of what their atmosphere might be like.”

The planet completes a single orbit around the red dwarf star every two Earth days. Given that the star is less than half the temperature of our sun, it is possible that the planet could still retain an atmosphere even though it is close to the star.

The researchers believe their discovery will be the first of many in the future for the Web.

“These first observational results from an Earth-sized, rocky planet open the door to many future opportunities to study rocky planet atmospheres with Webb,” said Mark Klampin, director of the Astrophysics Division at NASA Headquarters. “Webb is bringing us ever closer to a new understanding of Earth-like worlds beyond the Solar System, and the mission is just getting started.”

Dusty disc

More Webb observations were shared at Wednesday’s meeting, including never-before-seen images of a dusty disk orbiting a nearby red dwarf star.

The telescope’s images represent the first time such a disk has been imaged at these infrared wavelengths, which are invisible to the human eye.

A dusty disk called AU Mic around the star represents remnants of planet formation. When small, solid bodies called planetesimals — a planet in the making — collided, they left a large, dusty ring around the star, forming a debris disk.

“The debris disk is continuously replenished by colliding planetesimals. By studying it, we provide a unique window into the recent dynamical history of this system,” said lead author Kellen Lawson, a postdoctoral fellow at NASA’s Goddard Space Flight Center in Greenbelt. Member of research team studying Maryland and AU Mic.

We’ve barely scratched the surface of what their atmosphere might be like.

-Jacob Lustig-Yaeger, researcher

Webb’s capabilities allowed astronomers to see the region close to the star. Their observations and data may provide insights into the search for giant planets that form large orbits in planetary systems unlike Jupiter and Saturn in our solar system.

The AU Mic disk is located 32 light-years away in the constellation Microscopium. The star is about 23 million years old, so the formation of planets around the star has already stopped – because the process usually takes less than 10 million years, according to the researchers. Other telescopes observed two planets orbiting the star.

“This system is one of the very few examples of a young star with known exoplanets and a debris disk that is close enough and bright enough to study in its entirety using Webb’s uniquely powerful instruments,” said lead researcher Josh Schlieder, co-author of the study. for the observation program at NASA’s Goddard Space Flight Center.

The formation of stars

The Webb telescope was also used to look inside NGC 346, a star-forming region in a neighboring dwarf galaxy called the Small Magellanic Cloud.

About 2-3 billion years after the big bang that created the universe, galaxies were filled with fireworks of star formation. This peak of star formation is called “cosmic noon”.

“At cosmic noon, one galaxy wouldn’t have one NGC 346 like the Small Magellanic Cloud; it would have thousands,” said Margaret Meichner, an astronomer at the University Space Research Association and principal investigator of the research team. .

“Even if NGC 346 is now the one and only massive cluster in its galaxy forming stars furiously, it offers us a wonderful opportunity to probe the conditions that exist at cosmic noon.”

Observing how stars form in this galaxy allows astronomers to compare star formation in our own Milky Way galaxy.

In the new Webb image, the forming stars can be seen pulling gas and dust like ribbons from the surrounding molecular cloud. This material feeds the formation of stars and eventually planets.

“We see the building blocks not only of stars, but potentially planets,” researcher Guido De Marchi, a member of the European Space Agency’s space science faculty, said in a statement. “And because the Small Magellanic Cloud has an environment similar to that of galaxies at cosmic noon, it’s possible that rocky planets formed earlier in the history of the Universe than we think.”

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