Researchers from the Instituto de Astrofísica de Andalucía (IAA-CSIC) have made a groundbreaking discovery of a binary star system containing Earth-like planets orbiting between two celestial bodies. This marks the first time such a system has been identified, providing new insights into planet formation and stability.
Binary star systems, consisting of two stars that revolve around a common center, are common throughout the galaxy. However, detecting planets within these systems poses significant challenges due to the complex gravitational interactions between the two stars, which complicate both the formation and stability of any potential planets. Consequently, each new discovery within these environments is crucial for understanding where and how planets can emerge.
The IAA-CSIC team co-led the identification of a compact binary system known as TOI-2267. This system consists of two small, cool stars categorized as M5 and M6 types, which orbit unusually close to one another. Remarkably, it also includes two terrestrial-sized planets that transit in front of both stars, a previously unprecedented occurrence.
According to Francisco J. Pozuelos, an IAA-CSIC researcher, “In known binary systems with planets, they have always been found orbiting a single star, or in rare cases, both, but those stars were typically much farther apart.” He emphasized that TOI-2267 represents a unique and important finding, detailed in the latest publication of Astronomy & Astrophysics.
Located approximately 190 light-years from Earth, the TOI-2267 system features its stars separated by a distance equivalent to about eight times that between the Earth and the Sun. This close proximity creates a complex gravitational environment that is generally not conducive to planet formation. Despite this, researchers have identified three planets similar in size to Earth, all of which have short orbital periods.
“Our discovery breaks several records as it is the most compact and coolest star pair known to host planets, and it is the first to have planets transiting around both components,” Pozuelos noted.
The contribution of IAA-CSIC has been pivotal in this discovery. Utilizing their proprietary exoplanet search software named SHERLOCK, the team detected two of the three planets in this system even before the data reached NASA. This early detection allowed them to plan follow-up observations with ground-based telescopes, gaining over a year of advantage compared to other international teams, which was vital for leading this study.
Among these observations, crucial data was gathered using the 1.5-meter telescope at the Sierra Nevada Observatory in southern Spain, which provided essential information for understanding this unique planetary system.
“This discovery compels us to rethink current theories of planet formation in binary systems,” Pozuelos concluded.
