Mid-infrared spectroscopy of protoplanetary and planetary nebulae

Rinehart, Stephen A.; Houck, J. R.; Smith, John David; Wilson, J. C.

doi:10.1046/j.1365-8711.2002.05707.x

Cited by 8 publications

(8 citation statements)

References 26 publications

(26 reference statements)

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“…The SWS spectrum of M 4‐18 is very noisy, although the PAH features are unquestionably detected. However, the spectral levels of the PAH bands in this SWS spectrum match those in the spectrum by Rinehart et al (2002) to within 10 per cent, confirming our estimate of I (7.7)/ I (IR) for this object. In the small sample of PNe studied by Cohen et al (1989), NGC 6302 substantively helped to define the trend at 7.7 μm because of its low C/O ratio.…”

Section: Resultssupporting

confidence: 84%

“…M 4‐18 has the largest value of I (7.7)/ I (IR). Ground‐based spectra (Aitken & Roche 1982; Rinehart et al 2002) clearly show its 11.3‐μm band although its 8.7‐μm feature is convincingly shown only by the Aitken & Roche (1982) spectrum from Mauna Kea. The SWS spectrum of M 4‐18 is very noisy, although the PAH features are unquestionably detected.…”

Section: Resultsmentioning

confidence: 99%

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Polycyclic aromatic hydrocarbon emission bands in selected planetary nebulae: a study of the behaviour with gas phase C/O ratio

Cohen¹,

Barlow²

2005

Monthly Notices of the Royal Astronomical Society

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Airborne and space-based low-resolution spectroscopy in the 1980s discovered tantalizing quantitative relationships between the gas phase C/O abundance ratio in planetary nebulae (PNe) and the fractions of total far-infrared (FIR) luminosity radiated by the 7.7-and 11.3-µm bands (the C = C stretch and C-H bend, respectively), of polycyclic aromatic hydrocarbons (PAHs). Only a very small sample of nebulae was studied in this context, limited by airborne observations of the 7.7-µm band, or the existence of adequate IRAS Low Resolution Spectrometer data for the 11.3-µm band. To investigate these trends further, we have expanded the sample of planetaries available for this study using Infrared Space Observatory (ISO) lowresolution spectra secured with the Short Wavelength Spectrometer and the Long Wavelength Spectrometer. The new sample of 43 PNe, of which 17 are detected in PAH emission, addresses the range from C/O = 0.2-13 with the objective of trying to delineate the pathways by which carbon dust grains might have formed in planetaries. For the 7.7-µm and 11.3-µm bands, we confirm that the ratio of band strength to total infrared (IR) luminosity is correlated with the nebular C/O ratio. Expressed in equivalent width terms, the cut-on C/O ratio for the 7.7-µm band is found to be 0.6 +0.2 −0.4 , in good accord with that found from sensitive ground-based measurements of the 3.3-µ band.

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Section: Resultssupporting

confidence: 84%

Section: Resultsmentioning

confidence: 99%

Polycyclic aromatic hydrocarbon emission bands in selected planetary nebulae: a study of the behaviour with gas phase C/O ratio

Cohen¹,

Barlow²

2005

Monthly Notices of the Royal Astronomical Society

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“…Recent Spitzer observations show that planetary nebulae (PNe) in the LMC often show strong SiC emission (Stanghellini et al 2007;Bernard-Salas et al 2008), while in Galactic PNe, it is generally weak (Barlow 1983;Rinehart et al 2002). The presence of SiC features in EROs and PNe in the LMC suggests that (a) SiC grains are formed more abundantly in the LMC than previous recognized (e.g., Zijlstra et al 2006); and (b) that the LMC metallicity allows SiC to form and survive in the late AGB phase and into the PN phase more efficiently than in the Galaxy.…”

Section: Spectral Featuresmentioning

confidence: 99%

Discovery of Extreme Carbon Stars in the Large Magellanic Cloud

Gruendl

Chu

Seale

et al. 2008

ApJ

123

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Using Spitzer IRAC and MIPS observations of the Large Magellanic Cloud, we have identified 13 objects that have extremely red mid-IR colors. Follow-up Spitzer IRS observations of seven of these sources reveal varying amounts of SiC and C2H2 absorption as well as the presence of a broad MgS feature in at least two cases, indicating that these are extreme carbon stars. Preliminary estimates find these objects have luminosities of 4-11x10^3 Lsol and preliminary model fitting gives mass-loss rates between 4x10^-5 and 2x10^-4 Msol/yr, higher than any known carbon-rich AGB star in the LMC. These spectral and physical properties require careful reconsideration of dust condensation and mass-loss processes for carbon stars in low metallicity environments.Comment: Accepted for publication in ApJ Letters. 4 pages, 3 figure

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“…Whereas SiC is commonly seen in C-star spectra, its occurrence in Galactic (Milky Way) planetary nebulae (PNe) is less common (Barlow 1983;Rinehart et al 2002;Casassus et al 2001), even though C-stars evolve into C-rich PNe. However, evolution of these grains from the C-star to PNe phase is not understood, and other spectral features (e.g., ∼ 11 − 12µm plateau due to PAH emission) may mask the SiC band (see Speck & Hofmeister 2004).…”

Section: Potential Uses Of New Data On N and K For Sic Over The Ir To Uvmentioning

confidence: 99%

“…Detection of an SiC feature near 11 µm provides a diagnostic for the nature of these objects. Furthermore, SiC is commonly found in extreme carbon stars and planetary nebulae (PNe) in the Large Magellanic Cloud (Stanghellini et al 2007;Bernard-Salas et al 2008;Gruendl et al 2008), and not commonly found in their Milky Way counterparts (Barlow 1983;Rinehart et al 2002;Casassus et al 2001;Speck et al 2009). Consequently SiC presents a tool for understanding the effect of metallicity on dust formation, evolution, and survival.…”

Section: Introductionmentioning

confidence: 99%

Optical Constants of Silicon Carbide for Astrophysical Applications. Ii. Extending Optical Functions From Infrared to Ultraviolet Using Single-Crystal Absorption Spectra

Hofmeister¹,

Pitman²,

Goncharov

et al. 2009

ApJ

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Laboratory measurements of unpolarized and polarized absorption spectra of various samples and crystal stuctures of silicon carbide (SiC) are presented from 1200-35,000 cm −1 (λ ∼ 8-0.28 µm) and used to improve the accuracy of optical functions (n and k) from the infrared (IR) to the ultraviolet (UV). Comparison with previous λ ∼ 6-20 µm thin-film spectra constrains the thickness of the films and verifies that recent IR reflectivity data provide correct values for k in the IR region. We extract n and k needed for radiative transfer models using a new "difference method", which utilizes transmission spectra measured from two SiC single-crystals with different thicknesses. This method is ideal for near-IR to visible regions where absorbance and reflectance are low and can be applied to any material. Comparing our results with previous UV measurements of SiC, we distinguish between chemical and structural effects at high frequency. We find that for all spectral regions, 3C (β-SiC) and the E⊥ c polarization of 6H (a 1 currently at Planetary Science Institute, Tucson, AZ, 85719 -2type of α-SiC) have almost identical optical functions that can be substituted for each other in modeling astronomical environments. Optical functions for E c of 6H SiC have peaks shifted to lower frequency, permitting identification of this structure below λ ∼ 4µm. The onset of strong UV absorption for pure SiC occurs near 0.2 µm, but the presence of impurities redshifts the rise to 0.33 µm. Optical functions are similarly impacted. Such large differences in spectral characteristics due to structural and chemical effects should be observable and provide a means to distinguish chemical variation of SiC dust in space.

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Mid-infrared spectroscopy of protoplanetary and planetary nebulae

Cited by 8 publications

References 26 publications

Polycyclic aromatic hydrocarbon emission bands in selected planetary nebulae: a study of the behaviour with gas phase C/O ratio

Polycyclic aromatic hydrocarbon emission bands in selected planetary nebulae: a study of the behaviour with gas phase C/O ratio

Discovery of Extreme Carbon Stars in the Large Magellanic Cloud

Optical Constants of Silicon Carbide for Astrophysical Applications. Ii. Extending Optical Functions From Infrared to Ultraviolet Using Single-Crystal Absorption Spectra

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