The impact of companions on the rotation of Praesepe early M dwarfs

Binary companions likely affect stellar rotational evolution via tides (for close binaries) and disruption of the protoplanetary disk (for binary semimajor axes out to at least 5 to 80 AU). However, models of angular momentum evolution assume that all stars are single, and tidal models for solar-type stars cannot explain the handful of existing observations. Previous work on the Praesepe open cluster showed that half of rapidly rotating M dwarfs were candidate binaries, with few confirmed multiples. We have therefore surveyed 51 M0-M1 members of the Praesepe open cluster, using adaptive optics and non-redundant aperture masking at Keck II, to expand the binary sample and test the relationship between binary orbital separation and rotation period. All of our targets already have rotation period measurements. Our core sample includes 19 companions and 5 probable chance alignments. We then combine detection limits from additional AO data, WIYN/Hydra radial velocities, and Gaia astrometry to rule out companions at a wider range of projected separation.