A Survey of 3 to 5.4 Micron Emission From Planetary Nebulae using SOFIA/FLITECAM

TL;DR

This study uses airborne infrared spectroscopy to analyze PAH dust emission features in three planetary nebulae, providing insights into their chemical composition and evolution before star formation.

Contribution

First airborne spectroscopic survey of 3-5.4 μm PAH features in planetary nebulae, comparing ground and airborne data, and characterizing PAH and aliphatic emissions.

Findings

PAH emission observed in all three nebulae

Different aliphatic features among the nebulae

Detection of PAH at 5.25 μm in all targets

Abstract

Here we present the results of an airborne 3-5.4$\mu$m spectroscopic study of three young, Carbon-rich planetary nebulae IC 5117, PNG 093.9-00.1, and BD $+$30 3639. These observations were made using the grism spectroscopy mode of the FLITECAM instrument during airborne science operations onboard NASA's Stratospheric Observatory for Infrared Astronomy (SOFIA). The goal of this study is to characterize the 3.3 $\mu$m and 5.25 $\mu$m PAH dust emission in planetary nebulae and study the evolution of PAH features within evolved stars before their incorporation into new stellar systems in star-forming regions. Targets were selected from IRAS, KAO and ISO source lists, and were previously observed with FLITECAM on the 3-meter Shane telescope at Lick Observatory to allow direct comparison between the ground and airborne observations. We measure PAH emission equivalent width and central wavelength, classify the shape of the PAH emission, and determine the PAH/Aliphatic ratio for each target. The 3.3 $\mu$m PAH emission feature is observed in all three objects. PNG 093.9-00.1 exhibits NGC 7027-like aliphatic emission in the 3.4 to 3.6 $\mu$m region while IC 5117 and BD +30 3639 exhibit less aliphatic structure. All three PNs additionally exhibit PAH emission at 5.25 $\mu$m.