Signature of non-isotropic distribution of stellar rotation inclination angles in the Praesepe cluster

TL;DR

This study reveals that main sequence F-K stars in the Praesepe cluster exhibit a non-isotropic distribution of stellar rotation axes, suggesting possible rotational axis alignment within the cluster.

Contribution

It provides the first evidence of non-isotropic stellar rotation axis distribution in an open cluster using combined photometric and spectroscopic data.

Findings

Most likely inclination angle is 76±14 degrees.

Half opening angle of the inclination distribution is 47±24 degrees.

Non-isotropic distribution is favored over isotropic, barring overestimation of rotation velocities.

Abstract

The distribution of the stellar rotation axes of 113 main sequence stars in the open cluster Praesepe are examined by using current photometric rotation periods, spectroscopic rotation velocities, and estimated stellar radii. Three different samples of stellar rotation data on spotted stars from the Galactic field and two independent samples of planetary hosts are used as control samples to support the consistency of the analysis. Considering the high completeness of the Praesepe sample and the behavior of the control samples, we find that the main sequence F - K stars in this cluster are susceptible to rotational axis alignment. Using a cone model, the most likely inclination angle is 76+/-14 degrees with a half opening angle of 47+/-24 degrees. Non-isotropic distribution of the inclination angles is preferred over the isotropic distribution, except if the rotation velocities used in this work are systematically overestimated. We found no indication of this being the case on the basis of the currently available data.