For a long time, scientists believed that having two stars in one system would make it difficult for planets to form.
The strong gravitational pull between the stars was thought to create a chaotic environment, too unstable for planets to grow.
Worlds like Tatooine from Star Wars, with two suns in the sky, were often seen as rare exceptions rather than something common in the universe.
But new research is changing that view. Scientists from the University of Lancashire have found that planets may actually form more easily around binary stars—systems with two stars—than around single stars like our Sun.
Their findings were published in the journal Monthly Notices of the Royal Astronomical Society.
The researchers used advanced computer simulations to study how disks of gas behave around young binary stars. These disks are important because they are where planets are born. The simulations revealed something interesting.
Close to the two stars, there is a highly unstable region where strong gravitational forces make it nearly impossible for planets to form. The researchers call this area a “forbidden zone.”
However, things change further away from the stars. Beyond this dangerous inner region, the gas disk becomes much calmer and more suitable for planet formation. In these outer areas, the disk can break apart under its own gravity, a process known as fragmentation. This allows multiple planets to form quickly, especially large gas giants similar to or even bigger than Jupiter.
The study suggests that binary star systems might actually produce more planets than single-star systems. In addition, many of these planets are likely to be massive gas giants. Some may even be thrown out of their systems entirely due to gravitational interactions, becoming free-floating planets that drift through space on their own.
These findings help explain why astronomers have already discovered more than 50 planets that orbit two stars. Some of these planets exist on wide orbits, far from their stars, which fits well with the new model. It also suggests that such planets may be more common than scientists once thought.
The research opens up exciting possibilities for future discoveries. Powerful telescopes like ALMA, the James Webb Space Telescope, and the upcoming Extremely Large Telescope could help scientists observe these distant systems in more detail and confirm how planets form in them.
Overall, the study shows that while the area near two stars may be too chaotic for planet formation, the outer regions can become highly productive environments. This means that real-life versions of “two-sun” worlds may not be rare at all, but instead a common feature of our galaxy.
