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Astronomers have found another way that lone planets, not tied to any star, can form. A new study suggests that such objects may arise from collisions in gas and dust disks around young stars. The discovery explains why so many of these cosmic wanderers are observed in young star clusters, and why they often exist in pairs.
A team of international researchers led by Hongping Deng of the Shanghai Astronomical Observatory has modeled the interaction of circumstellar disks in young star clusters. When such disks collide at a speed of 2-3 km/s at a distance of 300-400 astronomical units, gravitational "tidal bridges" of gas arise. Over time, they collapse and form compact planet-like objects. Scientists estimate that up to 14% of such objects form in the form of binary or triple systems.
Previously, it was thought that such planet-like masses were either failed stars or planets that had been ejected from their systems. However, these theories did not explain why many of them move in sync with their star clusters and why they so often occur in pairs. The new results show that they arise not as remnants of other processes, but as a distinct class of celestial bodies.
Another feature of these objects is their composition. Because they form on the periphery of stellar disks, their chemical composition differs from that of typical exoplanets. Many of them harbor gaseous disks up to 200 astronomical units in diameter, which could theoretically lead to the formation of satellites or even smaller planets.
Scientists plan to continue studying these objects to better understand their chemical makeup and disk structure. Further observations will help confirm a new theory of their origin and explain why such lonely worlds are so common in the universe.
Astronomers have found another way that lone planets, not tied to any star, can form. A new study suggests that such objects may arise from collisions in gas and dust disks around young stars. The discovery explains why so many of these cosmic wanderers are observed in young star clusters, and why they often exist in pairs.
A team of international researchers led by Hongping Deng of the Shanghai Astronomical Observatory has modeled the interaction of circumstellar disks in young star clusters. When such disks collide at a speed of 2-3 km/s at a distance of 300-400 astronomical units, gravitational "tidal bridges" of gas arise. Over time, they collapse and form compact planet-like objects. Scientists estimate that up to 14% of such objects form in the form of binary or triple systems.
Previously, it was thought that such planet-like masses were either failed stars or planets that had been ejected from their systems. However, these theories did not explain why many of them move in sync with their star clusters and why they so often occur in pairs. The new results show that they arise not as remnants of other processes, but as a distinct class of celestial bodies.
Another feature of these objects is their composition. Because they form on the periphery of stellar disks, their chemical composition differs from that of typical exoplanets. Many of them harbor gaseous disks up to 200 astronomical units in diameter, which could theoretically lead to the formation of satellites or even smaller planets.
Scientists plan to continue studying these objects to better understand their chemical makeup and disk structure. Further observations will help confirm a new theory of their origin and explain why such lonely worlds are so common in the universe.
