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 μm 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.

14 pages, 15 figures, Accepted for publication in MNRAS

References in corpus (30)

• The Spitzer Space Telescope Mission
• The Infrared Spectrograph on the Spitzer Space Telescope
• Spectral Mapping Reconstruction of Extended Sources
• Investigating the Near-Infrared Properties of Planetary Nebula II. Medium Resolution Spectra
• Knots in the Helix Nebula found in H2
• Investigating the Near-Infrared Properties of Planetary Nebulae. I. Narrowband Images
• IRAC Observations of Planetary Nebulae
• Infrared Observations of The Helix Planetary Nebula
• Alpha Element Abundances in a Large Sample of Galactic Planetary Nebulae
• Spitzer Mapping of PAHs and H2 in Photodissociation Regions
• H2 and Br-gamma narrow-band imaging of bipolar planetary nebulae
• The Near-Infrared Structure and Spectra of the Bipolar Nebulae M 2--9 and Afgl 2688: The Role of UV-Pumping and Shocks in Molecular Hydrogen Excitation
• Herschel images of NGC 6720: H2 formation on dust grains
• Near Infrared Spectra of Compact Planetary Nebulae
• Morphology and kinematics of Planetary Nebulae II. A Diabolo model for NGC 3132
• A Butterfly in the Making: Revealing the Near- Infrared Structure of Hubble 12
• VLT / Infrared Integral Field Spectrometer Observations of Molecular Hydrogen Lines in the Knots in the Planetary Nebula NGC 7293 (the Helix Nebula)
• Near-IR spectroscopy of planetary nebulae precursors
• Molecular Hydrogen in the Ionized Region of Planetary Nebulae
• On the relationship between the H2 emission and the physical structure of planetary nebulae
• H2 infrared line emission from the ionized region of planetary nebulae
• The Halos of Planetary Nebulae in the Mid-Infrared: Evidence for Interaction with the Interstellar Medium
• Planetary Nebulae Detected in the Spitzer Space Telescope GLIMPSE II Legacy Survey
• High resolution imaging of NGC 2346 with GSAOI/GeMS: disentangling the planetary nebula molecular structure to understand its origin and evolution
• Bubbles and Knots in the Kinematical Structure of the Bipolar Planetary Nebula NGC 2818
• The Unusual Distributions of Ionized Material and Molecular Hydrogen in NGC 6881: Signposts of Multiple Events of Bipolar Ejection in a Planetary Nebula
• Planetary Nebulae Detected in the Spitzer Space Telescope GLIMPSE 3D Legacy Survey
• Optical and Mid-Infrared Observations of the Planetary Nebula NGC 6781
• Spitzer Mid-Infrared Observations of Seven Bipolar Planetary Nebulae
• Modelling the Warm H2 Infrared Emission of the Helix Nebula Cometary Knots

Cited by in corpus (9)

• The JWST Early Release Observations
• The Herschel Planetary Nebula Survey (HerPlaNS) - a comprehensive dusty photoionization model of NGC6781
• The MUSE view of the planetary nebula NGC 3132
• UOCS-IX. AstroSat/UVIT study of the open cluster NGC 2818: Blue Stragglers, Yellow Stragglers, Planetary Nebula, and their membership
• Unveiling the stellar origin of the Wolf-Rayet nebula NGC6888 through infrared observations
• Low-ionization structures in planetary nebulae -- III. The statistical analysis of physico-chemical parameters and excitation mechanisms
• The physical association of planetary nebula NGC 2818 with open cluster NGC 2818A
• Detection of the [C I] $\lambda$8727 emission line. Low-ionization structures in NGC 7009
• H${}_2$ molecular gas in the old planetary nebula NGC 3587