Webb confirms first exoplanet

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Science and exploration

11/01/2023 4755 views 61 likes

Researchers have confirmed the existence of an exoplanet, a planet orbiting another star, using the NASA/ESA/Canadian Space Agency’s James Webb Space Telescope for the first time. Officially classified as LHS 475 b, the planet is roughly the same size as our own, at 99% the diameter of Earth.

Exoplanet LHS 475 b and its star (illustration)

The research team is led by Kevin Stephenson and Jacob Lustig-Yeger, both of the Johns Hopkins University Applied Physics Laboratory in Laurel, Maryland. The team chose to monitor this target with Webb after carefully reviewing data from NASA’s Transiting Exoplanet Survey Satellite (TESS) that hinted at the planet’s presence. The Webb’s Near Infrared Spectrometer (NIRSpec) captured the planet easily and clearly with just two transit observations. “There is no doubt that the planet exists. The fact that it is a small, rocky planet is impressive for the observatory,” Lustig-Yeger said.

Exoplanet LHS 475 b (illustration)

“These first observational results from a rocky, Earth-sized planet open the door to many future possibilities for studying the atmospheres of rocky planets using Webb,” agreed Mark Clampin, director of the Astrophysics Division at NASA Headquarters in Washington. “Webb is bringing us closer and closer to a new understanding of Earth-like worlds outside the solar system, and the mission is still in its infancy.”

Of all the working telescopes, only Webb can describe the atmospheres of Earth-sized exoplanets. The team attempted to assess what was in the planet’s atmosphere by analyzing its transmission spectrum. Although the data shows that this is a terrestrial planet the size of Earth, they don’t yet know if it has an atmosphere. “The observatory’s data is beautiful,” said Irene May, of the Applied Physics Laboratory at Johns Hopkins University. “The telescope is so sensitive that it can easily detect a range of particles, but we can’t yet draw any definitive conclusions about the planet’s atmosphere.”

Exoplanet LHS 475 b (NIRSpec transit light curve)

Although the team can’t deduce what is there, they can certainly determine what isn’t. “There are some terrestrial atmospheres that we can rule out,” Lustig-Yaeger explained. “It could not have a dense, methane-dominated atmosphere, similar to that of Saturn’s moon Titan.”

The team also notes that although the planet likely has no atmosphere, there are some atmospheric compositions that have not been ruled out, such as a pure carbon dioxide atmosphere. “Unexpectedly, the atmosphere of 100% carbon dioxide is so much more compact that it becomes very difficult to detect,” said Lustig-Yaeger. More precise measurements are required for the team to distinguish a pure atmosphere of carbon dioxide from no atmosphere at all. The researchers are set to obtain additional spectra with further observations this summer.

Exoplanet LHS 475 b (NIRSpec Transmission Spectrum)

Webb also revealed that the planet is a few hundred degrees warmer than Earth, so if the clouds are detected, it could lead researchers to conclude that Venus-like Venus, which has a carbon dioxide atmosphere and is permanently shrouded in a dense cloud. “We are at the forefront of studying small, rocky exoplanets,” said Lustig-Yaeger. “We’ve barely begun to scratch the surface of what the atmosphere might be like.”

The researchers also confirmed that the planet completes its orbit in just two days, information revealed almost instantaneously by Webb’s delicate light curve. Although LHS 475 b is closer to its star than any planet in the solar system, its red dwarf star is less than half the temperature of the sun, so researchers speculate that it can still support an atmosphere.

The researchers’ findings open up the possibility of identifying Earth-sized planets orbiting smaller red dwarf stars. “The confirmation of this rocky planet highlights the precision of the mission’s instruments,” Stevenson said. “And it’s just the first of many discoveries she’ll make.” Lustig-Yaeger agreed: “With this telescope, rocky exoplanets are the new frontier.”

LHS 475 b is relatively nearby, only 41 light-years away, in the constellation Octane.

The team’s findings were presented at an American Astronomical Society (AAS) news conference on Wednesday, January 11, 2023.

More information Webb is the largest and most powerful telescope ever launched into space. Under an international cooperation agreement, ESA provided the telescope launch service, using the Ariane 5 launch vehicle. Working with partners, ESA was responsible for developing and qualifying Ariane 5 modifications for the Webb mission and procuring the launch service by Arianespace. ESA also provided the NIRSpec spectrometer and 50% mid-infrared MIRI instrument, which was designed and built by the nationally funded Consortium of European Institutes (MIRI Consortium) in partnership with JPL and the University of Arizona.

Webb is an international partnership between NASA, the European Space Agency, and the Canadian Space Agency (CSA).

ESA Media Relations: [email protected]

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