The Mid-Infrared Colours of Galactic Bulge, Disk and Magellanic Planetary Nebulae

TL;DR

This study analyzes mid-infrared photometry of planetary nebulae across the Galactic bulge, disk, and LMC, revealing similarities and differences in luminosity functions and MIR colors, and suggesting spectral and emission variations among these sources.

Contribution

It provides a comparative analysis of MIR colors and luminosity functions of planetary nebulae in different galactic environments using Spitzer data, highlighting spectral emission differences.

Findings

LMC and bulge sources have similar 3.6 micron luminosity functions.

LMC nebulae show different MIR color indices from Galactic counterparts.

More evolved disk sources have similar colors to less evolved sources, contrary to previous studies.

Abstract

We present mid-infrared (MIR) photometry for 367 Galactic disk, bulge and Large Magellanic Cloud (LMC) planetary nebulae, determined using GLIMPSE II and SAGE data acquired using the Spitzer Space Telescope. This has permitted us to make a comparison between the luminosity functions of bulge and LMC planetary nebulae, and between the MIR colours of all three categories of source. It is determined that whilst the 3.6 microns luminosity function of the LMC and bulge sources are likely to be closely similar, the [3.6]-[5.8] and [5.8]-[8-0] indices of LMC nebulae are different from those of their disk and bulge counterparts. This may arise because of enhanced 6.2 microns PAH emission within the LMC sources, and/or as a result of differences between the spectra of LMC PNe and those of their Galactic counterparts. We also determine that the more evolved disk sources listed in the MASH catalogues of Parker et al. and Miszalski et al. (2008) have similar colours to those of the less evolved (and higher surface brightness) sources in the catalogue of Acker et al. (1992); a result which appears at variance with previous studies of these sources.