The binary star system TOI-2267 likely contains two warm Earth-sized exoplanets and another Earth-sized candidate, according to the study. new paper published in the magazine Astronomy and astrophysics.
The artist's impression of the binary star system TOI-2267. Image credit: Mario Suserchia, University of Grenoble Alpes.
TOI-2267 consists of an M5 type star TOI-2267A and an M6 type star TOI-2267B with a predicted distance of approximately 8 AU.
The system, also known as G 222-3 or TIC 459837008, is located approximately 22 parsecs (73.5 light years) from our Sun in the constellation Cepheus.
“Our analysis reveals a unique planetary arrangement, with two planets transiting one star and a third transiting its companion star,” said Dr. Sebastian Zúñiga-Fernández, an astronomer at the University of Liège.
“This makes TOI-2267 the first known binary system to have transiting planets around both of its stars.”
“Our discovery breaks several records, as it is the most compact and coolest pair of stars with known planets, as well as the first to have planetary transits recorded around both components,” said Dr. Francisco Pozuelos, an astronomer at the Institute of Astrophysics of Andalusia.
Astronomers discovered three planetary signals using the SPECULOOS and TRAPPIST telescopes, as well as their proprietary SHERLOCK detection software.
“Finding three Earth-sized planets in such a compact binary system is a unique opportunity,” said Dr Zúñiga-Fernández.
“This allows us to test the limits of planet formation models in complex environments and better understand variety of possible planetary architectures in our Galaxy.”
The two confirmed planets, TOI-2267b and TOI-2267c, have orbital periods of 2.28 and 3.49 days.
From the current data set, the authors cannot determine which binary star these worlds orbit.
They are the size of the Earth with radii of 1 and 1.14 Earth radii for TOI-2267b and TOI-2267c respectively when orbiting TOI-2267A, while the radii are 1.22 and 1.36 Earth radii when orbiting TOI-2267B.
In addition to the signals attributed to TOI-2267b and c, the researchers detected a third strong signal with a periodicity of 2.03 days.
Its status remains that of a planetary candidate with a size of 0.95 or 1.13 Earth radii in orbit TOI-2267A or B, respectively.
“This system is a true natural laboratory for understanding how rocky planets can form and survive in extreme dynamic environments where we previously thought their stability would be compromised,” Dr Pozuelos said.
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S. Zuniga-Fernandez etc.. 2025. Two warm Earth-sized exoplanets and an Earth-sized binary candidate M5V-M6V TOI-2267. A&A 702, A85; two: 10.1051/0004-6361/202554419
