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Published online by Cambridge University Press: 19 July 2016
Kinematic study of the multiple shell PN NGC 3242 was carried out by obtaining Hα and [O III] line profiles at 9 positions of the nebula using a high-resolution (R ≅ 50,000) Fabry-Pérot spectrometer. The positions cover both the bright inner shell and the faint outer shell. It is shown here that the two apparently continuous shells are kinematically separate: the faint outer shell was ejected ∼ 5000 years earlier and has less expansion velocity than the bright inner shell.