Astronomers using NASA’s James Webb Space Telescope have discovered a giant planet outside our solar system, called an exoplanet, hiding within one of the most intensely studied planetary systems in our Milky Way galaxy.

The young, nearby star Beta Pictoris was already known to host two giant planets: Beta Pictoris b, one of the first exoplanets ever directly imaged, and Beta Pictoris c. The newly identified Beta Pictoris d makes it only the second planetary system known to contain at least three imaged planets. Unlike Beta Pictoris b and c, however, Beta Pictoris d was discovered not by identifying a bright point of light, but by detecting the unique chemical fingerprint of its atmosphere, a technique that could transform the search for worlds around other stars.

“This discovery adds another piece to an already fascinating planetary system,” said Aidan Gibbs, lead author of a new study published Wednesday in the Astrophysical Journal Letters and a postdoctoral researcher at the University of California, San Diego. “Beta Pictoris has long served as a laboratory for understanding how planetary systems form and evolve, and now we have another planet helping us tell that story.”

Image: Beta Pictoris System (Artist’s Concept)

Familiar system, new surprise

Located 63 light-years from Earth and about 23 million years old, Beta Pictoris is a nearby system in the Milky Way offering a rare glimpse of the interactions between newborn planets and the disk of dust and debris left behind from their formation. 

The team estimates that the newfound Beta Pictoris d is likely at least two times the mass of Jupiter, making it the smallest of the three known giant planets in the system. Modeling suggests it likely circles around its star at about 30 astronomical units, comparable to the region occupied by Neptune in our own solar system. It’s the widest orbit of the known three planets, but still located inside the inner edge of the debris disk.

Although astronomers were not searching for another planet with Webb, Beta Pictoris d emerged while the team was using the telescope’s NIRSpec (Near-Infrared Spectrograph) to study the atmosphere of Beta Pictoris b. Specifically, they used NIRSpec’s Integral Field Unit, which obtains both an image and a spectrum from each pixel in an image.

“We weren’t looking for a new planet,” said Gibbs. “We were trying to understand one we already knew existed. Then, this telltale signal appeared in the data where we didn’t expect it.”

This signal was a series of peaks and troughs within the spectroscopic data where the team expected to see a smooth spectrum from light bouncing off dust. It was a distinctive pattern of carbon monoxide absorption lines, spread out like a barcode, an expected feature in giant planet atmospheres.

Because spectroscopy not only reveals chemical composition, but the motion of an object, the team was able to also extract radial velocity from the data. The team determined the planet’s speed, position, and alignment with the debris disk were all consistent with something orbiting Beta Pictoris rather than a background star or brown dwarf with carbon monoxide in its atmosphere.

“There was an unexpected bright source of light within the Integral Field Unit imaging, but we’ve learned not to trust bright blobs in images,” said Jean-Baptiste Ruffio, a research scientist at University of California, San Diego and principal investigator of the first Webb observations where the discovery was made. “They can be instrumental artifacts or other structures in the debris disk. By obtaining a spectrum at the same time as the image, we were able to quickly confirm our suspicions.”

Follow-up observations with Webb’s MIRI (Mid-Infrared Instrument) through a Director’s Discretionary Time request detected water vapor and methane, further confirming the planet’s identity while providing a richer look at the atmosphere of the planet.

Unlike traditional imaging, the spectroscopic approach allowed researchers to identify the planet and begin studying its atmosphere from the very first observation. 

“A spectrum contains an incredible amount of information,” Ruffio said. “You don’t just learn that something is a planet; you immediately begin learning about its temperature, chemistry, and motion.”

A separate imaging study led by Ben Sutlieff of the University of Edinburgh and Markus Bonse of the European Southern Observatory complements the team’s findings with data from the European Southern Observatory’s Very Large Telescope and Webb’s NIRCam (Near-Infrared Camera) and independently confirmed the existence of Beta Pictoris d.

Image: Beta Pictoris System (NIRSpec IFU Image and Spectrum)

Image: Beta Pictoris System (NIRSpec IFU Image Annotated)

Seeing through cosmic fog

Beta Pictoris d remained hidden for years because it lies within one of the brightest debris disks known.

The dusty disk acts like fog, scattering light from the star, making it difficult for conventional imaging techniques to distinguish planets from surrounding structures. The team’s spectroscopic method with Webb effectively ignored that dust, isolating only the narrow molecular signatures unique to a planetary atmosphere.

Scientists say the planet’s presence may help explain why the famous debris disk has such a sharply defined inner edge and other puzzling structures. In fact, astronomers had already predicted the existence of a planet like Beta Pictoris d to account for the disk’s unusual structure.

Beyond expanding our understanding of Beta Pictoris, the discovery demonstrates a powerful new way to find exoplanets.

This is the first directly imaged planet discovered primarily through moderate-resolution spectroscopy, showing that astronomers can identify worlds in complex environments through their atmospheric fingerprints rather than relying solely on traditional coronagraphic imaging.

The researchers plan to continue analyzing Webb’s observations to better determine the planet’s temperature, atmospheric composition, and orbit, providing an even more detailed view of one of astronomy’s most iconic planetary systems.

The James Webb Space Telescope is the world’s premier space science observatory. Webb is solving mysteries in our solar system, looking beyond to distant worlds around other stars, and probing the mysterious structures and origins of our universe and our place in it. Webb is an international program led by NASA with its partners, ESA (European Space Agency) and CSA (Canadian Space Agency).

To learn more about Webb, visit:

https://science.nasa.gov/webb

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Read more: Webb’s Impact on Exoplanet Research

Read more: NASA’s Webb Discovers Dusty ‘Cat’s Tail’ in Beta Pictoris System

Explore more: Beta Pictoris: Icy Debris Suggests ‘Shepherd’ Planet

Watch: How to Study Exoplanets: Webb and Challenges

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NASA’s James Webb Space Telescope is giving us new insight into the far-future of solar systems like our own, as the agency continues to reveal the secrets of the universe and our place in it. Billions of years ago, a Sun-like star nearing the end of its life swelled tremendously in size to become a red giant before ejecting its outer layers, leaving a hot, remnant core known as a white dwarf. As a red giant, the star should have engulfed and destroyed any nearby planets. Yet astronomers have found a Jupiter-sized exoplanet orbiting the white dwarf every 34 hours at a separation of less than 2 million miles (3 million kilometers).

To solve the mystery of how this exoplanet survived, an international team of astronomers used NASA’s James Webb Space Telescope to watch the Jupiter-sized exoplanet WD 1856 b transit its host star, measuring the planet’s temperature and detecting molecules in its atmosphere. They found the planet is significantly warmer than expected and determined how it most likely reached its very tight orbit around the white dwarf star. The results are a window into the future of planets like Jupiter after the death of the Sun, billions of years into the future.

The results published Wednesday in the journal Nature.

WD 1856 b was discovered in 2020 by scientists using NASA’s TESS (Transiting Exoplanet Survey Satellite) and the retired Spitzer Space Telescope. It orbits the white dwarf WD 1856+534, which is located about 80 light-years from Earth. “The planet is about the size of Jupiter, but the white dwarf it orbits is the size of Earth, so the planet is seven times larger than its star,” said lead author Ryan MacDonald of the University of St. Andrews in the United Kingdom.

WD 1856 b orbits extremely close to its host star, a distance 50 times closer than Earth orbits the Sun. If WD 1856 b had originally been orbiting at that distance, it would have been obliterated while the star was a red giant. How did it survive the death of its host star and end up in its current position?

Image: Exoplanet WD 1856 b (Artist’s Concept)

How big, how hot

The new study used Webb to watch the planet passing in front of its star. This transit yielded unique information about the planet’s mass, which is between four and eleven times the mass of Jupiter.

The team also was able to determine the planet’s temperature. During the transit, light from the star was partly blocked, but infrared light was reduced less than other wavelengths. The difference was infrared light emitted by the planet from its own heat. The data indicated that the planet has a temperature of about 260 degrees Fahrenheit (126 degrees Celsius) — significantly hotter than it would be if its only source of heat was the light from the white dwarf. This puzzling discovery turned out to be the key fact that proved how the planet must have reached its current orbit.

Christopher O’Connor of Northwestern University in Illinois, a co-author on the paper, was responsible for tracing the temperature of the planet back in time. O’Connor said, “The big question is how WD 1856 b ended up where it is today, and there are two theories. One is that the planet was swallowed by the host star as it was dying, and managed to survive on the inside. The other is that migration took place due to the gravitational effect of other objects in the system. The white dwarf is part of a triple star system, and the companion stars could have influenced WD 1856 b’s orbit.”

The researchers realized that there was no source of energy present to generate that heat today, so it must be residual energy from an earlier time when the planet was heated. Using models of how sub-stellar objects like WD 1856 b cool down over time, coupled with the new data from Webb, the team was able to project its temperature back in time and deduce how long ago the heating must have happened. The timing is key to determining whether the heating was from being engulfed by the red giant or occurred during an inward migration

They concluded that the heating most likely happened between 3 and 5.5 billion years after the star became a white dwarf. In this scenario, the planet was on a wide orbit that kept it safe from the star during its destructive red giant phase, and only migrated to its present location later on. “As the planet moved inward, its interactions with the strong gravity of the white dwarf will have caused it to warm up considerably, and it has been cooling ever since,” said O’Connor.

Light from the star passing through the planet’s atmosphere also picked up information about its chemical composition. “We saw the telltale signatures of small cloud particles and hydrocarbons, most likely methane, which is the first time we have seen an atmosphere on a planet transiting a dead star,” said co-author Victoria Boehm of Cornell University. “We recently observed four more transits of WD 1856 b with Webb to take a deeper look into its atmospheric chemistry and can’t wait to see the results.”

Image: Exoplanet WD 1856 b (Transmission Spectrum)

Solar system’s possible future

In approximately five billion years, the Sun will run out of hydrogen fuel in its core and swell up more than 100 times larger than it is now into a red giant star. It will then shed its outer layers and end its life as a white dwarf star. Mercury, Venus, and possibly the Earth will be destroyed by the red giant. However, the fate of the more distant planets, particularly the gas giants, is unclear. Finding and studying planets in orbit around the remnants of Sun-like stars after their death is a means of learning what might happen in our own solar system in the far future.

“We’re used to looking back in time when we use telescopes, but this is the first time we have been able to look forward to what might happen to the outer planets around the remnant of a Sun-like star,” said MacDonald. “It’s like using a time machine to peer into the distant future of our solar system.”

The James Webb Space Telescope is the world’s premier space science observatory. Webb is solving mysteries in our solar system, looking beyond to distant worlds around other stars, and probing the mysterious structures and origins of our universe and our place in it. Webb is an international program led by NASA with its partners, ESA (European Space Agency) and CSA (Canadian Space Agency).

To learn more about Webb, visit:

https://science.nasa.gov/webb

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The following sections contain links to download this article’s images and videos in all available resolutions followed by related information links, media contacts, and if available, research paper and Spanish translation links.

Related Links

Read more: Webb’s Impact on Exoplanet Research

Explore more: ViewSpace | Exoplanet Variety: Atmosphere

Explore more: How to Study Exoplanets: Webb and Challenges

Watch: Giant World Circles a Tiny Star

Explore more: ViewSpace | Star Death: Helix Nebula

More Webb: News | Images | Science | Home Page

For the first time, NASA’s TESS (Transiting Exoplanet Survey Satellite) mission has identified a planet orbiting a distant star thanks to ripples in space-time. Unlike the star-hugging transiting planets TESS regularly reveals, the newfound world is a super-Jupiter orbiting far from its host star.

“When TESS launched, no one expected it to ever be capable of finding this kind of planet,” said Diana Dragomir, a professor at the University of New Mexico in Albuquerque and co-author of a paper describing the results. At 1.6 times Jupiter’s mass and a similar orbital distance, it would be extremely unlikely to find such a planet via the primary detection method TESS was designed for. “The discovery implies that there are probably other so-called microlensing planets hiding in TESS’s data that we hadn’t previously thought to look for.”

Astronomers found the first hint of the planet, called Gaia23bra b, in 2023 using ESA’s (European Space Agency) now-retired Gaia space telescope. Gaia’s alert system flagged a star that brightened — something that can happen when a foreground star passes in front of a more distant one and magnifies its light through gravitational microlensing.

Researchers later looked back through archived TESS data and found TESS had caught it too.

“Gaia’s observations were too sparse to pick up on the planet,” said Mallory Harris, a Ph.D. candidate at the University of New Mexico, who led the study. “The TESS spacecraft happened to be monitoring the same area of the sky during the event, and its denser time coverage showed extra features in the light curve caused by a planet.”

The team’s analysis, published July 1 in The Astrophysical Journal Letters, revealed that Gaia23bra b, which orbits an orange dwarf star that’s about 80 percent of the Sun’s mass, is nearly 40,000 light-years away from Earth, far exceeding TESS’s usual search radius of about 150 light-years.

Microlensing 101

Out of more than 6,000 known exoplanets (worlds outside our solar system), about three-fourths were discovered via the transit method, TESS’s typical planet-hunting technique. Astronomers monitor hordes of stars, watching for ones that periodically dim as orbiting planets cross in front of them — an event called a transit.

Microlensing has revealed less than 5% of known exoplanets. This light-bending phenomenon occurs when two stars align closely from our vantage point. Light from the more distant star curves as it travels through the warped space-time caused by the nearer star’s mass.

If the alignment is especially close, the nearer star acts like a cosmic lens, focusing and magnifying light from the background star. Planets orbiting the foreground star may also modify the distant star’s light, acting as their own tiny lenses. Astronomers see the effect as a spike in the star’s brightness.

The transit method is best at finding large planets orbiting very close to their host stars; large planets block the most starlight, while close-in planets are more likely to pass in front of the host star. These gargantuan, steamy worlds are fascinating to scientists, but astronomers want to find planets like those in our solar system, too. That’s microlensing’s specialty.

Microlensing isn’t well suited to finding huge, close-in planets because their gravitational signals would just blur together.

“Transits and microlensing are complementary because they each reveal a category of planet the other may not be able to detect,” Dragomir said. “And they offer different details. Transits give us the size of a planet, and in concert with other methods we can determine its mass and density. Microlensing gives us masses and orbital distances for planets we’d otherwise never see.”

But microlensing observations are time-limited opportunities.

That makes detailed observations of microlensing planets tough. However, the method can serve as a powerful demographics tool that offers broad information about planetary populations.

“This is a bit like a preview of the microlensing NASA’s Nancy Grace Roman Space Telescope will do,” said Michael Fausnaugh, a professor at Texas Tech University in Lubbock and a co-author of the study. On track for launch on August 30, 2026, Roman will observe the center of the Milky Way galaxy for one of its core surveys, revealing an estimated 1,000 microlensing planets and around 100,000 transiting planets.

Roman will specifically target the heart of the galaxy because stars are packed so tightly together there, increasing the odds of seeing microlensing events. While that crowding would make many stars blend together in TESS’s larger pixels, TESS looks at nearly the whole sky, where stars are ​more spread out.

“Since TESS looks elsewhere in the galactic plane, it can naturally find microlensing planets in other parts of the galaxy, as demonstrated by this first microlensing planetary system,” Dragomir said. “That means it could help us study planets in regions with different conditions.”

That could have implications for the search for habitable worlds. The bustling galaxy center is rife with radiation from more frequent supernova explosions, which could sterilize planets. And gravitational encounters between crowded stars may disrupt planetary systems. Observations from TESS focus on a milder part of the galaxy.

“The key to Roman’s microlensing survey is its dense time coverage targeting the galactic bulge,” Fausnaugh said. “The TESS mission uniquely provides these rapid observations for stars in other parts of the galaxy, and pairing the two opens up prospects for understanding planet formation in a diverse population of stars. Since microlensing finds solar system-like planets, this offers a new chance to understand how planetary systems like our own vary in different regions of the galaxy.”

To learn more about the TESS mission, visit:

https://www.nasa.gov/tess

Media contact:

Claire Andreoli
NASA’s Goddard Space Flight Center, Greenbelt, Md.
301-286-1940