Astrophysicists at Northwestern University have unveiled a computational technique that effectively “turns off” the blinding glare of distant stars, allowing the James Webb Space Telescope (JWST) to reveal planets that were previously hidden in its own archival data. The method, called FLIP (Physics-based Learning for Imaging Planets), has already recovered a giant exoplanet, 51 Eridani b, from observations taken two years earlier where conventional processing had failed to detect it. The findings were published in the journal Nature.
- Digital Twin Approach: FLIP creates a virtual replica of Webb’s Near Infrared Camera (NIRCam) to simulate and subtract starlight with unprecedented precision.
- Hidden Planet Recovered: The technique revealed 51 Eridani b, a gas giant about 11 times Jupiter’s mass located 97 light-years away, in existing Webb data.
- Significant Sensitivity Boost: Tests showed FLIP improves detection sensitivity for faint exoplanets by 2 to 15 times compared to conventional image processing methods.
The Starlight Problem and the FLIP Solution
Directly imaging exoplanets is extraordinarily difficult because stars vastly outshine their planetary companions. Even the most advanced space telescopes struggle to separate the faint light of a planet from the overwhelming brightness of its host star. Webb uses coronagraphs—masks that block most of a star’s light—but they cannot block all of it. Astronomers typically subtract the remaining glare using a reference image of a different star. However, tiny telescope movements and vibrations, such as those from the cooling system motors of the NIRCam instrument, make that reference imperfect, leaving behind residual starlight that can bury even a large planet.
FLIP takes a different approach. Instead of borrowing another star’s image, it builds a detailed physical model—a digital twin—of the telescope that simulates how starlight travels through Webb’s optics to its detector. The researchers adjusted millions of parameters to account for small misalignments and optical distortions, then subtracted the simulated glare from the original observations. “This is the first time that we have demonstrated that these little imperfections or instabilities are not a limiting factor in the kinds of planets we can image,” said lead author Rodrigo Ferrer-Chavez, a graduate student at Northwestern University in the lab of astronomer Jason Wang, who is also a co-author.
“Because we already know the physics, we don’t need AI to understand what’s happening,” co-author Jason Wang told Live Science. “We’re showing how computation can help overcome limitations of the telescope itself.”
Recovering 51 Eridani b and Validating the Method
The team tested FLIP on archival Webb data from its NIRCam instrument for three stars: HIP 65426, 51 Eridani, and TYC 5899, a star with no known planets. With FLIP, 51 Eridani b appeared at a detection strength above 5 sigma, the threshold astronomers commonly use for a confident signal. The planet, a young gas giant about 97 light-years from Earth, had been discovered in 2015 with ground-based telescopes but could not be distinguished in Webb’s earlier observations. Its atmosphere contains carbon dioxide, which absorbs light at 4.3 microns—a wavelength Webb can observe—making it a valuable target for studying the chemistry of a young giant planet.
In tests involving known planets, FLIP achieved two to 15 times greater detection sensitivity than conventional approaches. The gain varied by target, but the implication is broad: Webb’s public archive may already contain planets that standard processing could not reveal. “We demonstrate that we can recover a planet that people previously could not see,” Wang said, emphasizing that this is “real data in a real scenario.” Ferrer-Chavez added that the underlying frustration is that planets resembling those in our own solar system likely exist but remain hidden because current tools cannot see them.
Implications for Future Exoplanet Research
The significance of FLIP extends beyond a single recovery. Because the method works on data already collected, astronomers can rerun it on years of Webb coronagraph observations, potentially finding smaller, colder planets without hardware changes. The team plans to improve FLIP and test its performance with other instruments, including the Nancy Grace Roman telescope and ground-based observatories. According to the Northwestern release, the technique may also ease the extreme picometer-level stability that NASA’s proposed Habitable Worlds Observatory would otherwise need. That observatory is intended to image Earth-like planets around Sun-like stars, and relaxing its stability requirements could affect its engineering and cost.
However, the result should be read carefully. FLIP recovered a planet that was already known, not a new world, and the study tested the method on only three stars. The 15-fold improvement is the upper end of the range; the typical gain on other targets was smaller. The method also depends on how well the digital twin matches the real telescope. Independent teams will need to apply FLIP to more Webb data, and to other instruments, before astronomers know how widely the gains hold. Any new planet candidate found in archival images would still require follow-up observations to confirm it is a planet and not background noise or a distant object.
Nevertheless, the study shows that better modeling of a telescope’s quirks can unlock faint signals that were previously thrown away with the glare. By extracting more science from data already collected, FLIP stretches the investment in Webb without another launch—a compelling reminder that software can be as powerful as hardware in the quest to understand distant worlds.
Sources & References