JWST’s First Exoplanet Images Forecast a Bright Future

JWST’s First Exoplanet Images Forecast a Bright Future

The James Webb Space Telescope has taken first images of a distant planet. The planet, known as HIP 65426 b, is a gas giant several times more massive than Jupiter, circling its star at a distance that is about three times greater than the separation between Neptune and our sun. HIP 65426 b is only around 15 million years old–a newborn in astronomical terms–and roughly 350 light-years from Earth.

While you might not be impressed with the detail in these new planetary photos, the researchers who took them were. “I had to ensure that I wasn’t looking at a simulation image when the results came back,” said Sasha Hinkley , a professor of Astrophysics at the University of Exeter, England. It looked exactly like the model images we used when we submitted our proposal five years ago .”

The images of HIP 65426 b reveal that JWST is outperforming expectations for its exoplanet studies, which are one of the telescope’s four central research areas. This means that JWST’s planned attempts to observe other exoplanets is likely to be more successful than researchers expected. Astronomers can also get more ambitious when submitting proposals for JWST governing board in future research cycle.

JWST may not be the first telescope to photograph exoplanets directly, but it is already the best. Hinkley has seen the field evolve: he’s been working on exoplanet imaging for almost 20 years. “I was really intrigued by the technical challenges of this research–of having to block out these incredibly bright host stars, which are 10,000 or a million times brighter than the faint planets orbiting them,” he says.

This feat almost seems impossible. It’s like spotting a dimly lit firefly from your seat, looking across the field. Exoplanets are possible if you have the right technique.

” We can observe a nearby star with similar properties to our target star,” said study co-author Aarynn Cart ,, a postdoctoral researcher at University of California, Santa Cruz who led the analysis for this exoplanet image. “Then, we can basically build a template of how the starlight looks and subtract that away to leave only the planet .”

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This sounds simple but it takes a lot to make this work. They did just that, even more than Carter and Hinkley expected.

JWST had an imaging sensitivity that was even higher than expected. Its advanced coronagraph was able to block out most of the light from the host star. JWST was also extremely stable during its observations, which is perhaps the most important aspect of this study. To subtract the first star from the second, it is essential to have stability.

” We saw that James Webb is so stable that the [starlight] patterns are stable from star to star,” Hinkley states. “And this is really due to the incredible work that has been done by literally thousands of scientists and technicians and engineers over the last 20 years across the entire globe.”

Charles Beichman, director of NASA’s Exoplanet Science Institute, helped develop the JWST research instruments that Hinkley and Carter used in their imaging. He says that when you launch something, you build it to a set requirements. And then you have a set of what we call ‘desirements.'”

With the most recent exoplanet photos, it is now clear that JWST instruments are meeting everyone’s expectations. Beichman states that JWST has tighter images, less jitter, and the detectors perform a bit better. JWST’s proven level of stability and sensitivity means that it can directly observe smaller exoplanets in the past than any other telescope. This is even more than researchers had hoped.

That’s excellent news for future studies, including one that will be led by Beichman between July and August 2023 that will use direct imaging to look for planets within our nearest star system, Alpha Centauri.

Astronomers have so far only been able to photograph exoplanets several times larger than Jupiter, orbiting far from their stars. Hinkley states that we now know that James Webb will probably get us down to analogues for our Saturn or Neptune, based on these observations.

Sebastian Marino, an astronomy research fellow at Jesus College at the University of Cambridge, is one likely beneficiary of JWST’s expectation-shattering overperformance. Between next April and June Marino and his colleagues plan to observe stars that are surrounded by wide debris disks that resemble gargantuan versions of Saturn’s rings. Marino’s team will be focusing on a few disks with noticeable gaps. They believe that exoplanets, as yet undiscovered, are responsible for “carving” these gaps as they orbit their host star.

Based on the widths of the gaps, Marino predicts these exoplanets (if any) will be around the same mass and mass as Saturn and Neptune. Although detecting them was an ambitious goal at first, the latest imaging results show that JWST can detect planets of these sizes. Hinkley also notes that this is a new capability.

” The fact that it’s performing well than we thought is really encouraging,” Marino states. Marino is happy that JWST will be able confirm the existence of exoplanets even if they don’t find them. One of the most important aspects of planet hunting is knowing when it’s time to stop searching for worlds around a star. Marino states that a weaker telescope would yield inconclusive findings that could only prolong what could be a futile search.

The latest exoplanet images also bode well for Elisabeth Matthews, a postdoctoral researcher at the University of Geneva. Matthews states that “for my own program it’s validating seeing that the instrument really works as well as we anticipated when we designed it.”

Between April and May 2023 Matthews will use JWST to observe a nearby planet-bearing star–Epsilon Indi A, only 12 light-years away. The star’s exoplanet Epsilon Indi A is only known by the subtle gravitational wobble that its bulk causes on the star. Although no one has seen it directly, astronomers have made best guesses that it is quite old. Giant exoplanets are believed to have been created hot and radiate enormous amounts of heat energy from their creation. (The glowing planetary blob seen in JWST’s infrared images of HIP 65426 b is mostly thermal energy emitted by the planet itself, not light that’s reflecting off the tops of its clouds. )

Alder, cooler planets are generally too faint to photograph – they are drowned out by the bright lights of their host stars. Matthews’s plan of imaging a mature planet is difficult, but JWST’s recent performance suggests it should be possible. Matthews says she designed her study to take up the minimum amount of time needed to be able to produce a planetary image–but now she’s even more confident that it will succeed in that time frame because JWST’s greater-than-expected sensitivity is akin to being granted more observing time.

It’s too late to easily change plans for JWST’s inaugural “Cycle 1” observations to capitalize on its greater-than-anticipated high-contrast imaging performance, but these early results will certainly make astronomers more confident when planning future research. Matthews and Marino suggest that they might have bolder research targets next year. Research proposals for JWST’s second cycle of observations will be due in late January.

Sasha Hinkley will reach out to the astronomical world with advice about how to get the best out of JWST, based on the team’s new understanding of its capabilities. Hinkley states that he expects that the community will be able to present the strongest set of proposals to make these observations through his recommendations.

In future research cycles, targets that are too small or too far away to observe may be considered. And ultimately JWST’s superlative exoplanet imaging work should help guide efforts to develop even more ambitious observatories that can photograph not just gas giants but targets that are much smaller and fainter: potentially habitable, more Earth-like worlds.

“Proposals whose title was ‘Wow, we’ll be lucky if that’ have been elevated to ‘Yeah we should be able that’, says Beichman. “And a new set of things that were ‘There’s no way we could do that’ enter the realm of ‘Yeah, we’ve got a shot at pulling that off.'”

ABOUT THE AUTHOR(S)

    Daniel Leonard is a freelance science journalist and current S

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