Massive Stars Binary Stars Tidal Forces Star Clusters Solar Dynamics Star Formation Solar Activity Supernova Observations Dynamo Mechanism Gravitational Interactions Star Motion Star-Black Hole Interactions Star Orbits Energy Outbursts Magnetic Fields Solar Flares Star Mergers Cluster Dynamics Gravity Effects Rotation White Dwarfs Sun Intracluster Light Convection Supernovae Mass Transfer Triple Systems Solar System Evolution