For approximately the last fifteen years, definitive evidence of circumbinary planets—exoplanets that encircle binary stars—has been accumulating. Through analyses of data from NASA’s Kepler Space Telescope and the Transiting Exoplanet Survey Satellite (TESS), 14 such celestial bodies have been identified utilizing the transit detection technique. A recently developed methodology applied to TESS observational data has now brought to light 27 additional prospective circumbinary planets, suggesting that these unusual planetary configurations might be more prevalent than previously assumed.
An artist’s impression of a circumbinary exoplanet and its two parent stars. Image credit: Sci.News.
These newly identified planet candidates span a significant size spectrum, ranging from bodies potentially comparable in mass to Neptune, up to those exceeding Jupiter’s mass by a factor of ten.
Their distances from Earth vary considerably, with the nearest located approximately 650 light-years away and the most remote situated at a distance of roughly 18,000 light-years.
According to Ben Montet, an astronomer at the University of New South Wales and a co-author of the research, “The candidates are scattered across both our southern and northern skies.”
He further elaborated, “This spatial distribution implies that regardless of the time of year or observational orientation, at least one of these star systems remains observable, provided one possesses a telescope.”
The study’s findings indicate that “We identified 27 planet candidates from a sample of 1,590 binary star systems, which translates to an approximate 2% prevalence rate for binary systems capable of hosting planets.”
This observation leads to the projection that “There could potentially be thousands, or even tens of thousands, of undiscovered planets awaiting detection within the data generated by the Vera C. Rubin Observatory’s upcoming decade-long sky survey, the Legacy Survey of Space and Time.”
Montet expressed enthusiasm, stating, “This represents a truly promising initial stride, and it also underscores the substantial undertaking anticipated in the coming years.”
The innovative planet-detection methodology employed by the research team, termed apsidal precession, has previously been utilized for characterizing binary stars, though not on the scale of a comprehensive exoplanet survey.
This technique involves meticulous observation of the orbital dynamics between binary stars, evidenced by their stellar eclipses, over extended temporal intervals.
Any deviations in the timing of these eclipses that cannot be attributed to the principles of general relativity or intrinsic stellar interactions suggest the presence of a third celestial body exerting gravitational influence on the stellar orbits, potentially being a planet.
Margo Thornton, a Ph.D. candidate at the University of New South Wales and the lead author of the paper, commented, “A significant portion of our current planetary knowledge is inherently skewed by our detection methodologies.”
“We have predominantly identified the celestial bodies that are easiest to observe,” she added.
“This novel approach holds the potential to facilitate the discovery of a vast population of concealed planets, particularly those whose orbital planes are not perfectly aligned with our observational perspective.”
Thornton believes this method “could contribute to a more accurate representation of the true distribution of planets throughout the cosmos.”
Dr. Montet conveyed his excitement regarding the prospective number of planets discoverable through this technique, stating, “I am enthusiastic about the potential for uncovering a multitude of planets with this method.”
“I had not anticipated identifying 27 candidates so early in this pilot investigation,” he admitted.
“The next phase involves the truly engaging endeavor of verifying which of these candidates are indeed bona fide planets.”
The team’s findings have been published in the Monthly Notices of the Royal Astronomical Society and can be accessed via the following link: results.
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Margo Thornton et al. 2026. Detection of 27 candidate circumbinary planets through apsidal precession of eclipsing binaries observed by TESS. MNRAS 548 (3): stag515; doi: 10.1093/mnras/stag515
