演講資訊

摘要：

The kinematics of young stellar clusters hold critical clues about the dynamical state of their parent molecular clouds. Decades ago, Lynden-Bell demonstrated that violent relaxation during collapse results in a system with velocity dispersion independent of particle mass. In contrast, astronomers frequently expect that, if collisional relaxation occurs, energy equipartition between stars should happen, where massive stars exhibit smaller velocity dispersion than their lower-mass counterparts. Recently, we have found that stellar clusters, such as the Orion and Lagoon Nebula clusters, and numerical simulations of collapsing clouds, produce clusters where the stars have a constant velocity dispersion. However, turbulence-supported clouds tell a more complex story: massive newborn stars exhibit larger velocity dispersion than low-mass stars. Through an analysis of turbulent numerical simulations, I will demonstrate that this phenomenon arises as a consequence of a phenomenon we call "accretion-driven gravitational tightening", where massive stars form in denser, more crowded regions within turbulence-supported clouds, allowing them to accrete mass more efficiently while simultaneously interacting with nearby stars. In contrast, low-mass stars, which accrete less vigorously and tend to be more isolated, are not able to grow with the same intensity as their velocity dispersion.