Three Earth-Sized Planets Found Orbiting a Single Binary Star—Could Life Exist?

Three Earth-sized planets have recently been discovered by a global team of researchers in the binary stellar system TOI-2267, which is situated roughly 190 light-years away.

The formation and stability of planets in double-star environments—which have long been thought to be unsuitable for the development of complex planetary systems—are clarified by this astounding discovery, which was published in Astronomy & Astrophysics.

Sebastián Zúñiga-Fernández, researcher and member of the ExoTIC group at the University of Liège (ULiège) and first author of the study, said, “Our analysis shows a unique planetary arrangement: two planets are transiting one star, and the third is transiting its companion star.”

“This makes TOI-2267 the first binary system known to host transiting planets around both of its stars,” the researcher added.

The tight orbits of two stars in TOI-2267 make it a compact binary, which makes the planet-forming environment gravitationally unstable. However, in a startling discovery that calls into question a number of traditional theories of planetary formation, scientists have discovered three planets the size of Earth in brief orbits.

“Our discovery breaks several records, as it is the most compact and coldest pair of stars with planets known, and it is also the first in which planets have been recorded transiting around both components,” explains Francisco J. Pozuelos, a former member of the ExoTIC group and currently a researcher at the Instituto de Astrofísica de Andalucía (IAA-CSIC), and co-leader of the study.

Although the data came from NASA’s TESS space telescope, ULiège and IAA-CSIC astronomers used their own detection software, SHERLOCK, to identify two of the three planets initially. The team was able to initiate ground-based follow-up observations well in advance of this early discovery.

An extensive campaign involving multiple observatories was necessary to confirm the planetary nature of these signals later on. The ULiège-led SPECULOOS and TRAPPIST telescopes were crucial to these efforts. In order to confirm the planets and characterize the system, these robotic facilities—which were designed for studying small exoplanets around faint, cool stars—were essential.

“Discovering three Earth-sized planets in such a compact binary system is a unique opportunity,” explained Zúñiga-Fernández. “It allows us to test the limits of planet formation models in complex environments and to better understand the diversity of possible planetary architectures in our galaxy.”

Pozuelos further added, “This system is a true natural laboratory for understanding how rocky planets can emerge and survive under extreme dynamical conditions, where we previously thought their stability would be compromised.”

In addition to opening the door for new observations, particularly with the James Webb Space Telescope (JWST) and the upcoming generation of massive ground-based telescopes, this discovery poses numerous questions regarding planet formation in binary systems. These tools will make it possible to measure these far-off worlds’ masses, densities, and possibly even the makeup of their atmospheres with precision.

Beyond its breathtaking beauty, this discovery demonstrates how space missions can be combined with specialized ground-based telescopes like SPECULOOS and TRAPPIST to advance exoplanetary science.