A study of TESS data has uncovered 27 new candidate circumbinary planets, bringing the known total from 18 to 45. The results were published on May 4 in the Monthly Notices of the Royal Astronomical Society. The planets were identified using a method called apsidal precession, which detects minute changes in the timing of stellar eclipses caused by the gravitational pull of an unseen third body.
According to the study, these timing variations can arise from a combination of tidal, rotational, relativistic, and planetary effects. This technique, first detailed in the new study, allows astronomers to find circumbinary planets even when their orbits are not aligned edge-on as viewed from Earth, overcoming a significant limitation of traditional transit methods. Margo Thornton, a doctoral candidate at UNSW Sydney and lead author, explained that the survey searched for planets using these eclipse timing variations rather than direct transits, making it sensitive to planets in a wide range of orbital orientations.
The researchers analyzed TESS observations of 1,590 eclipsing binary systems, each with at least two years of data. Of these, 36 exhibited signs of a third body, and 27 of those are consistent with being planets. According to NASA, TESS has already confirmed 885 exoplanets and identified more than 7,900 candidates, and routinely monitors tens of thousands of eclipsing binary stars.
According to Margo Thornton and her colleagues, the candidate planets are located between 650 and 18,000 light years away. Thornton added that they range in size from Neptune-sized to ten times Jupiter's mass, which would classify some as super-Jupiters. More than half of all stars are estimated to exist in binary or multiple systems, according to astronomer Margo Thornton, making circumbinary planets a potentially vast population.
However, the true nature of these 27 candidates remains uncertain; they could be brown dwarfs or even low-mass stars, and further observations with ground-based telescopes or future space missions will be needed to confirm them. The precise masses and sizes are also yet to be determined. The new detection method opens up the possibility of discovering many more such worlds in the future, especially as TESS continues to gather data.