Spitzer Infrared Spectrograph Observations of Magellanic Cloud Planetary Nebulae: the nature of dust in low metallicity circumstellar ejecta

Abstract

We present 5 - 40 micron spectroscopy of 41 planetary nebulae (PNe) in the Magellanic Clouds, observed with the Infrared Spectrograph on board the Spitzer Space Telescope. The spectra show the presence of a combination of nebular emission lines and solid-state features from dust, superimposed on the thermal IR continuum. By analyzing the 25 LMC and 16 SMC PNe in our sample we found that the IR spectra of 14 LMC and 4 SMC PNe are dominated by nebular emission lines, while the other spectra show solid-state features. We observed that the solid-state features are compatible with carbon-rich dust grains (SiC, polycyclic aromatic hydrocarbons (PAHs), etc.) in most cases, except in three PNe showing oxygen-rich dust features. The frequency of carbonaceous dust features is generally higher in LMC than in SMC PNe. The spectral analysis allowed the correlations of the dust characteristics with the gas composition and morphology, and the properties of the central stars. We found that: 1) all PNe with carbonaceous dust features have C/O>1, none of these being bipolar or otherwise highly asymmetric; 2) all PNe with oxygen-rich dust features have C/O<1, with probable high mass progenitors if derived from single-star evolution (these PNe are either bipolar or highly asymmetric); 3) the dust temperature tracks the nebular and stellar evolution; and 4) the dust production efficiency depends on metallicity, with low metallicity environments not favoring dust production.

The Astrophysical Journal, in press

References in corpus (5)

• Lithium and zirconium abundances in massive Galactic O-rich AGB stars
• A New Population of Planetary Nebulae Discovered in the Large Magellanic Cloud (II): Complete PN Catalogue
• Hubble Space Telescope Images of Magellanic Cloud Planetary Nebulae
• The Mass Distribution of the Central Stars of Planetary Nebulae in the Large Magellanic Cloud
• Planetary nebulae as probes of the chemical impact of AGB stars

Cited by in corpus (6)

• Molecules and dust production in the Magellanic Clouds
• Optical properties of silicon carbide for astrophysical applications I. New laboratory infrared reflectance spectra and optical constants
• Discovery of Extreme Carbon Stars in the Large Magellanic Cloud
• Carriers of the mid-IR emission bands in PNe reanalysed. Evidence of a link between circumstellar and interstellar aromatic dust
• Carbon abundance in Small Magellanic Cloud planetary nebulae through Advanced Camera for Surveys prism spectroscopy: constraining stellar evolution at low metallicity
• The population of Magellanic Cloud planetary nebulae