The Timescale Correlation Method: Distances to Planetary Nebulae with Halos

摘要

We present deep narrow-band CCD images of six PNe obtained with the Palomar 5 m telescope in the light of [N II] λ6584 + Hα and [O III] λ5007. Several previously undetected structures are found, including faint multiple envelope structures surrounding three of the targets. The inclusion of these sources with data for other multiple envelope PNe published in the literature permit a statistical evaluation of the relationship between PN "shells" and the thermal pulses of the PN nucleus.