Original title: Rescuing Kepler's False Positives: A Possible Habitable Zone Exoplanet in the Triple Star System KOI-1623
Rita Lanxuan Wang, Daniel Huber, Daniel Hey, Nathanael Burns-Watson +5 · September 2026
Telescopes find exoplanets, or planets outside our solar system, by watching stars dim as planets pass in front of them. When the light seems to shift off-center during this dip, scientists usually dismiss the signal as a false alarm. But sometimes, two close stars blur together, and a real planet is simply orbiting one of them. Researchers looked closer at discarded data using the Gaia space catalog and the Keck telescope. They checked an ignored signal named KOI-1623.01, which repeats every 111 days. They discovered it is actually a triple star system. A giant planet orbits in the habitable zoneThe region around a star where temperatures could allow liquid water on a planet's surface—not too hot, not too cold. of the second star, where temperatures could allow liquid water. By checking more stars with Gaia, they estimate that about 70 out of 515 tossed-out signals are actually real planets in binary star systems.
Imagine you are in a dark room and you see a light flicker. You point toward it, but the direction seems a bit off. Normally you would dismiss it as a reflection from somewhere else. But what if the room has two lamps very close together, and the flicker is from one of them, not a reflection? In this paper the flicker is a planet crossing in front of one star in a pair, but the telescope's view was not sharp enough to tell the two stars apart, so it looked like a false signal from the wrong spot.
The Kepler mission found thousands of planet candidates, but many were tossed out as false positives due to a technical glitch. This paper shows that for at least one case, the glitch was misidentifying a real planet orbiting one star in a pair. If hundreds more were similarly misclassified, then our census of exoplanets is off, and we may have been ignoring planets that could be habitable.
The paper only rescues a single case—KOI-1623.01—via detailed follow-up. The extrapolation to ~70 other misclassified false positives is a statistical estimate based on Gaia's resolved binary catalog, not a direct confirmation. Each candidate would need its own follow-up to verify. Additionally, the rescued planet is a giant (10 R⊕), likely gaseous, not a rocky Earth analog, even though it lies in the habitable zone.
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Rescuing Kepler's False Positives: A Possible Habitable Zone Exoplanet in the Triple Star System KOI-1623 — Rita Lanxuan Wang, Daniel Huber, Daniel Hey et al.
Abstract licence: CC0
Explanation generated by Synthesis from the abstract — it is not the original paper. This is a preprint, so it hasn't necessarily been peer reviewed.