Located 190 light-years from Earth, the TOI-2267 system contains two stars — and, remarkably, each of them hosts planets
that transit, or pass in front of, their respective suns. This is the first confirmed case of planets transiting both
stars in a binary system.
The discovery, detailed in the journal Astronomy & Astrophysics, not only challenges existing theories of planetary
formation but also broadens the search for rocky worlds in binary environments once thought too unstable. The compact
nature of TOI-2267 makes it even more intriguing, with both stars closely orbiting each other in a gravitationally
intense dance. These extreme conditions, long believed hostile to planet formation, seem instead to have nurtured three
stable terrestrial worlds.
Behind this breakthrough is a coordinated effort between space-based and ground-based telescopes, combining data from
NASA’s TESS mission with follow-up observations by specialized instruments. According to the Instituto de Astrofísica de
Andalucía, the discovery pushes the boundaries of what we know about where rocky planets can emerge and endure — even
under gravitational duress.
A First-Of-Its-Kind Planetary Configuration
The TOI-2267 system presents a configuration never seen before: two planets transit one star, and a third transits the
other. Sebastián Zúñiga-Fernández, first author of the study and researcher at the University of Liège (ULiège),
described the setup as a “unique planetary arrangement” that establishes TOI-2267 as “the first binary system known to
host transiting planets around both of its stars,” reports Science Daily.
This arrangement is rare not only in its architecture but also in its physical properties. According to Francisco J.
Pozuelos of the Instituto de Astrofísica de Andalucía, TOI-2267 now holds multiple records. It is the most compact and
coldest known pair of stars to host planets, and the only one with confirmed transits across both stellar components. In
systems where stellar companions orbit in such close proximity, gravitational instability was previously expected to
prevent planet formation or at least disrupt long-term orbital stability.
Ground and Space Collaboration Unlocks Detection
Initial hints of TOI-2267’s planetary structure came from NASA’s Transiting Exoplanet Survey Satellite (TESS). The
telescope identified potential transit signals, which prompted further investigation using custom detection software
developed by the teams at ULiège and IAA-CSIC, known as SHERLOCK.
To verify the planets, researchers launched an extensive campaign using ground-based facilities. Key to this effort were
the SPECULOOS and TRAPPIST telescopes, robotic observatories operated by ULiège under principal investigator Michaël
These instruments specialize in tracking small exoplanets around faint, cool stars — precisely the conditions found in
the TOI-2267 system. The data they provided confirmed not only the existence of the three Earth-sized planets but also
offered critical insights into their orbital patterns and alignment within the binary structure.
A New Lens on Planetary Diversity
The system offers scientists a natural laboratory to test planet formation theories under extreme conditions.
“Discovering three Earth-sized planets in such a compact binary system is a unique opportunity,” said Zúñiga-Fernández,
noting that it allows researchers to explore how planetary systems can develop and survive despite dynamic instability.
Pozuelos, a co-leader of the study, echoed this sentiment, calling TOI-2267 “a true natural laboratory” that helps
illustrate the variety of planetary configurations in our galaxy. With conditions previously believed too disruptive for
stable planetary development, the system demonstrates that rocky planets can, in fact, emerge and persist even within
gravitationally complex environments.
According to the teams involved, this finding reinforces the need for continued cooperation between space and ground