C/O Abundance Ratios and Dust Features in Galactic Planetary Nebulae

TL;DR

This study investigates the relationship between iron depletion, dust features, and C/O ratios in Galactic planetary nebulae, revealing diverse dust compositions and depletion patterns linked to chemical abundances.

Contribution

It provides new insights into how dust formation and destruction processes vary with chemical composition in planetary nebulae, highlighting complex relationships between dust features and C/O ratios.

Findings

C/O < 1 PNe show increasing iron depletion with higher C/O

C-rich PNe exhibit diverse dust features including silicates and PAHs

Iron depletion varies widely, indicating different dust processing histories

Abstract

The iron depletion factors found in Galactic planetary nebulae (PNe) span over two orders of magnitude, suggesting that there are differences in the grain formation and destruction processes from object to object. We explore here the relation between the iron depletions, the infrared dust features, and the C/O abundance ratios in a sample of Galactic PNe. We find that those objects with C/O < 1 show a trend of increasing depletions for higher values of C/O, whereas PNe with C/O > 1 break the trend and cover all the range of depletions. Most of the PNe with C/O < 1 show silicate features, but several PNe with C-rich features have C/O < 1, probably reflecting the uncertainties associated with the derivation of C/O. PAHs are distributed over the entire range of iron depletions and C/O values.