New Exoplanet Candidates Discovered in Binary Star Systems by NASA TESS Data
Researchers from UNSW Sydney have identified dozens of candidate exoplanets using a novel method that detects gravitational tugs in binary systems, a technique capable of finding worlds traditional transit surveys often miss.
A study analysing data from NASA's Transiting Exoplanet Survey Satellite has identified more than two dozen candidate exoplanets orbiting binary star systems. By measuring precise eclipse timings in pairs of eclipsing stars, researchers detected gravitational tugs from planets that traditional transit methods could not find. The findings, published on 4 May in the Monthly Notices of the Royal Astronomical Society, include candidates ranging from 12 to approximately 3,200 Earth masses.
Study lead Margo Thornton from UNSW Sydney noted the discovery helps understand planet formation around two gravitationally bound stars. The research team, which includes Scientia associate professor Benjamin Montet, utilised a novel survey method searching for planets using stellar eclipses that is not limited to the orientation of the planet's orbit. This approach allowed them to analyse 1,590 binary star systems with at least two years of TESS data to reveal the 27 candidates awaiting confirmation.
Prior to this study, discoveries by NASA's retired Kepler mission and other facilities had recorded 16 transiting worlds around binary stars, while TESS had found an additional two. The new candidates represent a significant expansion of known systems, with mass estimates ranging from a minimum of 12 Earth masses to a maximum of roughly 3,200 Earth masses, which is approximately 10 times Jupiter's mass.
The timing of stellar eclipses can gradually change through tidal and rotational interactions between the stars, the effects of general relativity, and the presence of other unseen masses, such as planets, in the system. All of these forces cause the entire orbital plane of the binary to rotate, or precess, and this in turn alters the eclipse timing. This phenomenon provides the key to calculating the different influences and identifying the gravitational presence of potential planets.
Future ground-based observations are required to confirm the masses and velocities of these potential worlds. While the TESS mission was built to find transiting planets, it is great to see how the same measurements are driving discoveries far beyond its original mission. The mission's continuing data collection enables new findings across a wide range of astronomical topics, from asteroids in the solar system to active galaxies powered by black holes in the distant universe.
Since science operations began in 2018, TESS has tiled the sky by observing large swaths, called sectors, for nearly a month. Currently, the mission's cameras capture a single image of the entire sector, measuring 24 by 96 degrees, about every 3 minutes, with even faster observations of selected targets. This rich set of observations has proven essential for identifying the subtle signals of planets in complex binary environments.
