Spitzer mid-infrared spectroscopic observations of planetary nebulae
Abstract
We present Spitzer Space Telescope archival mid-infrared (mid-IR) spectroscopy of a sample of eleven planetary nebulae (PNe). The observations, acquired with the Spitzer Infrared Spectrograph (IRS), cover the spectral range 5.2-14.5 {\mu}m that includes the H2 0-0 S(2) to S(7) rotational emission lines. This wavelength coverage has allowed us to derive the Boltzmann distribution and calculate the H2 rotational excitation temperature (Tex). The derived excitation temperatures have consistent values ~900+/-70 K for different sources despite their different structural components. We also report the detection of mid-IR ionic lines of [Ar III], [S IV], and [Ne II] in most objects, and polycyclic aromatic hydrocarbon (PAH) features in a few cases. The decline of the [Ar III]/[Ne II] line ratio with the stellar effective temperature can be explained either by a true neon enrichment or by high density circumstellar regions of PNe that presumably descend from higher mass progenitor stars.
Keywords
Cite
@article{arxiv.1603.06667,
title = {Spitzer mid-infrared spectroscopic observations of planetary nebulae},
author = {Héctor Mata and Gerardo Ramos-Larios and Martin A. Guerrero and Alberto Nigoche-Netro and Jesús A. Toalá and Xuan Fang and Gabriel M. Rubio and Simon N. Kemp and Silvana G. Navarro and Luis J. Corral},
journal= {arXiv preprint arXiv:1603.06667},
year = {2016}
}
Comments
14 pages, 15 figures, Accepted for publication in MNRAS