Variability in C-rich proto-PNe.

We have carried out long-term (14 years) V and R photometric monitoring of 12 carbon-rich proto-planetary nebulae. The light and color curves display variability in all of them....本研究对12颗富碳原行星状星云（proto-planetary nebulae）开展了长达14年的V波段与R波段测光监测。所有目标的光变曲线与色变曲线均呈现出光变特性。