IAA authors:
Guerrero, M. A.;Toalá, J. A.;Fang, X.
Authors:
Mata, H.;Ramos-Larios, G.;Guerrero, M. A.;Nigoche-Netro, A.;Toalá, J. A.;Fang, X.;Rubio, G.;Kemp, S. N.;Navarro, S. G.;Corral, L. J.
Journal:
Monthly Notices of the Royal Astronomical Society
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 μm that includes the H<SUB>2</SUB> 0-0 S(2) to S(7) rotational emission lines. This wavelength coverage has allowed us to derive the Boltzmann distribution and calculate the H<SUB>2</SUB> rotational excitation temperature (T<SUB>ex</SUB>). 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.
URL:
https://ui.adsabs.harvard.edu/#abs/2016MNRAS.459..841M/abstract
Keywords:
(ISM:) planetary nebulae: individual (M 2-51;NGC 2346;NGC 2440;NGC 2818;NGC 3132;NGC 6072;NGC 6445;NGC 6537;NGC 6720;NGC 6781;NGC 7293;planetary nebulae: general;ISM: lines and bands;infrared: general;Astrophysics - Solar and Stellar Astrophysics;Astrophysics - Astrophysics of Galaxies