“Our analysis shows a unique planetary arrangement: two planets are transiting one star, and the third is transiting its companion star,” explains Sebastián Zúñiga-Fernández, a researcher at the University of Liège (ULiège) and first author of the paper. “This makes TOI-2267 the first binary system known to host transiting planets around both of its stars.”

A Compact and Unusual Double-Star System

TOI-2267 consists of two stars locked in a close orbital dance, forming what astronomers call a compact binary system. Such systems create gravitational forces that typically disrupt planet formation. Despite this, researchers have detected three Earth-sized planets in tight orbits, a surprising outcome that challenges long-held theories about where rocky worlds can exist.

“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,” says Francisco J. Pozuelos, a co-leader of the study and researcher at the Instituto de Astrofísica de Andalucía (IAA-CSIC).

Combining Space and Ground Observations

NASA’s TESS space telescope first provided the data leading to this discovery. Two of the planets were initially identified by astronomers at ULiège and IAA-CSIC using their custom software tool, SHERLOCK. This early detection prompted ground-based observations to confirm the findings.

The confirmation process required a major effort involving several observatories. Among the most important were the SPECULOOS and TRAPPIST telescopes operated by ULiège (PI: Michaël Gillon). Designed to detect small exoplanets around cool, dim stars, these robotic instruments were vital for verifying the planets and studying their characteristics in detail.

A Natural Testbed for Planet Formation

“Discovering three Earth-sized planets in such a compact binary system is a unique opportunity,” says 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 adds, “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.”

Looking Ahead to Future Exploration

The discovery opens up new questions about how planets form and persist in binary systems. Upcoming observations with the James Webb Space Telescope (JWST) and next-generation ground-based observatories could reveal more details, such as the planets’ masses, densities, and even their atmospheric compositions.

Beyond its scientific importance, the finding underscores the value of combining data from space-based observatories like TESS with precise ground-based instruments such as SPECULOOS and TRAPPIST. Together, they continue to expand our understanding of how planetary systems form and evolve across the galaxy.

Osteoporosis weakens bones, making them fragile and more likely to break. As Japan’s population continues to age, the number of people affected is projected to surpass 15 million. Among the various types of fractures caused by osteoporosis, compression fractures of the spine, known as osteoporotic vertebral fractures, are the most common. These injuries can result in long-term disability and severely reduce quality of life, highlighting the need for safer and more effective treatments.

How Fat-Derived Stem Cells Help Rebuild Bone

Stem cells derived from adipose tissue (ADSCs) show strong potential for repairing bone damage. These multipotent cells can develop into various types of tissue, including bone. When ADSCs are cultivated into three-dimensional spherical groups called spheroids, their ability to promote tissue repair increases. Pre-differentiating these spheroids toward bone-forming cells further enhances their effectiveness in stimulating bone regeneration.

Led by Graduate School of Medicine student Yuta Sawada and Dr. Shinji Takahashi, the Osaka research team used ADSCs to create bone-differentiated spheroids and combined them with β-tricalcium phosphate, a material commonly used in bone reconstruction. The mixture was applied to rats with spinal fractures, resulting in significant improvements in bone healing and strength.

The researchers also observed that genes responsible for bone formation and regeneration became more active after the treatment, suggesting that the approach stimulates the body’s natural healing processes.

Promising Outlook for Future Treatments

“This study has revealed the potential of bone differentiation spheroids using ADSCs for the development of new treatments for spinal fractures,” said Sawada. “Since the cells are obtained from fat, there is little burden on the body, ensuring patient safety.”

Dr. Takahashi added, “This simple and effective method can treat even difficult fractures and may accelerate healing. This technique is expected to become a new treatment that helps extend the healthy life of patients.”

The findings were published in Bone & Joint Research.