Variability in Protoplanetary Nebulae. X.

New observations are presented of four evolved objects that display long, multiyear variations in their light curves. These are interpreted as good evidence of their binary...本研究报道了四颗演化天体的观测结果，这些天体的光变曲线呈现出持续多年的长周期变化。上述观测结果被视为其为双星系统的有力佐证……