​Nearly four years of observations by NASA's Kepler space telescope of about fifty red giant stars, located in two clusters aged 2 and 8 billion years were processed by scientists. They analyzed the tiny variations of the stars' luminosity, reflecting the oscillation modes of their internal structure. Based on these data, they were able to accurately deduce the orientation of the spin axis of the stars. Their results showed that 70% of the stars in the same cluster have aligned spin axes, whereas models have so far predicted randomly distributed spin axes.

New three-dimensional hydrodynamic computer simulations show that the spin axes of the stars line up when at least 50% of the total energy balance of the  molecular cloud  giving rise to the cluster (proto-clusters) is associated with its rotation. Only stars with masses above 0.7 solar mass can "inherit" the initial rotational motion of the cloud and have aligned spin axes. The formation of other stars, less massive, is dominated by turbulence and the orientation of their spin axes is randomly distributed.

Additional confirmation of this discovery in other star clusters would put the conditions of star formation back into question.