Binary Star Formation Linked to Rapid Star Rotation

Recent research has revealed significant insights into the formation of fast-rotating stars, particularly those found in binary systems. The paper titled "Protostellar spin-up and fast rotator formation through binary star formation" by Rajika L. Kuruwita and colleagues investigates the correlation between binary star formation and the rapid rotation of stars, defined as having rotation periods of less than two days.

The study utilized magneto-hydrodynamical simulations to explore how the formation of companion stars influences the angular momentum of primary stars. The researchers found that the primary star can experience spin-up events correlated with the formation of companions. Specifically, the primary star can spin up by as much as 84% of its pre-fragmentation angular momentum due to gravitational disc instabilities in the circumstellar disc around it.

The simulations indicated that stronger disc instabilities lead to the formation of companions, while weaker instabilities may result from a companion's flyby without further fragmentation. This suggests that stars in multiple systems may end up spinning faster than single stars, potentially contributing to the population of fast rotators observed in the universe.

The findings have implications for understanding stellar evolution and the dynamics of star formation in binary systems. By linking companion formation to increased rotation rates, this research provides a new perspective on how stars evolve in complex environments. The study emphasizes the importance of considering binary interactions when examining the characteristics of stars, particularly in relation to their rotation speeds.

For further details, the full paper can be accessed here.