Cool clouds of interstellar gas collapse and form new stars. This process is a balance between gravity, pulling inwards, and turbulence, providing a counteracting pressure. The virial parameter is the ratio of twice the turbulent kinetic energy to the gravitational energy, and is different for different clouds with different properties, formation histories, evolutionary states, and environments. This visualization contrasts two magnetohydrodynamical simulations of protostellar formation. The left shows a low virial parameter (0.0625) case, while on the right is a high virial parameter (0.125) case.

Methods: FLASH code