Akari/Irc Near-Infrared Spectral Atlas of Galactic Planetary Nebulae

Ohsawa, Ryou; Onaka, Takashi; Sakon, Itsuki; Matsuura, M.; Kaneda, Hidehiro

doi:10.3847/0004-6256/151/4/93

Cited by 19 publications

(10 citation statements)

References 55 publications

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“…In many interstellar and circumstellar environments the 3.3 μm emission feature is indeed often accompanied by a weaker feature at 3.4 μm (see Li & Draine 2012, and references therein). The 3.4 μm emission feature itself is often also accompanied by several weak satellite features at 3.43, 3.46, 3.51, and 3.56 μm (e.g., see Geballe et al 1985;Jourdain de Muizon et al 1986;Joblin et al 1996;Sloan et al 1997Sloan et al , 2014Kaneda et al 2014;Mori et al 2014;Hammonds et al 2015;Ohsawa et al 2016). We define I 3.4 and I 3.3 as the observed intensities of the 3.4 and 3.3 μm emission features, respectively.…”

Section: Introductionmentioning

confidence: 99%

THE C–H STRETCHING FEATURES AT 3.2–3.5 μm OF POLYCYCLIC AROMATIC HYDROCARBONS WITH ALIPHATIC SIDEGROUPS

Yang

Glaser

et al. 2016

ApJ

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The so-called "unidentified" infrared emission (UIE) features at 3. 3, 6.2, 7.7, 8.6, and 11.3 μm are ubiquitously seen in a wide variety of astrophysical regions. The UIE features are characteristic of the stretching and bending vibrations of aromatic hydrocarbon materials, e.g., polycyclic aromatic hydrocarbon (PAH) molecules. The 3.3 μm aromatic C-H stretching feature is often accompanied by a weaker feature at 3.4 μm. The latter is generally thought to result from the C-H stretch of aliphatic groups attached to the aromatic systems. The ratio of the observed intensity of the 3.3 μm aromatic C-H feature to that of the 3.4 μm aliphatic C-H feature allows one to estimate the aliphatic fraction of the UIE carriers, provided that the intrinsic oscillator strengths of the 3.3 μm aromatic C-H stretch (A 3.3 ) and the 3.4 μm aliphatic C-H stretch (A 3.4 ) are known. While previous studies on the aliphatic fraction of the UIE carriers were mostly based on the A A 3.4 3.3 ratios derived from the mono-methyl derivatives of small PAH molecules, in this work we employ density functional theory to compute the infrared vibrational spectra of PAH molecules with a wide range of sidegroups including ethyl, propyl, butyl, and several unsaturated alkyl chains, as well as all the isomers of dimethylsubstituted pyrene. We find that, except for PAHs with unsaturated alkyl chains, the corresponding A A 3.4 3.3 ratios are close to that of mono-methyl PAHs. This confirms the predominantly aromatic nature of the UIE carriers previously inferred from the A A 3.4 3.3 ratio derived from mono-methyl PAHs.

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Section: Introductionmentioning

confidence: 99%

THE C–H STRETCHING FEATURES AT 3.2–3.5 μm OF POLYCYCLIC AROMATIC HYDROCARBONS WITH ALIPHATIC SIDEGROUPS

Yang

Glaser

et al. 2016

ApJ

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“…In addition to the 3.30 µm band, spectrum 2 also exhibits the 3.40 µm band, as well as minor bands at 3.43, 3.47, and 3.51 µm. All these bands have been seen in several sources (e.g., Pilleri et al 2015;Sloan et al 1997;Ohsawa et al 2016). They have been attributed to aliphatic bonds in methyl side groups attached to PAHs (Joblin et al 1996a) or in superhydrogenated PAHs (Bernstein et al 1996).…”

Section: Chemical Diversitymentioning

confidence: 96%

Learning mid-IR emission spectra of polycyclic aromatic hydrocarbon populations from observations

Foschino

Berné

Joblin

2019

A&A

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Context. The James Webb Space Telescope (JWST) will deliver an unprecedented quantity of high-quality spectral data over the 0.6-28 µm range. It will combine sensitivity, spectral resolution, and spatial resolution. Specific tools are required to provide efficient scientific analysis of such large data sets. Aims. Our aim is to illustrate the potential of unsupervised learning methods to get insights into chemical variations in the populations that carry the aromatic infrared bands (AIBs), more specifically polycyclic aromatic hydrocarbon (PAH) species and carbonaceous very small grains (VSGs). Methods. We present a method based on linear fitting and blind signal separation for extracting representative spectra for a spectral data set. The method is fast and robust, which ensures its applicability to JWST spectral cubes. We tested this method on a sample of ISO-SWS data, which resemble most closely the JWST spectra in terms of spectral resolution and coverage. Results. Four representative spectra were extracted. Their main characteristics appear consistent with previous studies with populations dominated by cationic PAHs, neutral PAHs, evaporating VSGs, and large ionized PAHs, known as the PAH x population. In addition, the 3 µm range, which is considered here for the first time in a blind signal separation (BSS) method, reveals the presence of aliphatics connected to neutral PAHs. Each representative spectrum is found to carry second-order spectral signatures (e.g., small bands), which are connected with the underlying chemical diversity of populations. However, the precise attribution of theses signatures remains limited by the combined small size and heterogeneity of the sample of astronomical spectra available in this study. Conclusions. The upcoming JWST data will allow us to overcome this limitation. The large data sets of hyperspectral images provided by JWST analysed with the proposed method, which is fast and robust, will open promising perspectives for our understanding of the chemical evolution of the AIB carriers.

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“…The near-IR band excess could be explained by including dust grains of smaller size, and also, polycyclic aromatic hydrocarbon (PAH) molecules. Indeed, Ohsawa et al (2016) reports the detection of a neutral PAH band at 3.3 𝜇m. However, since the PAH mass fraction concerning the dust mass would be very small, as confirmed in other C-rich PNe (e.g., Otsuka et al 2017;Otsuka & Hyung 2020), the derived GDR and dust mass are not largely modified even while doing so.…”

Section: Photoionisation Modelingmentioning

confidence: 99%

Seimei KOOLS-IFU Mapping of the Gas and Dust Distributions in Galactic Planetary Nebulae: the Case of IC2165

Otsuka

2022

Preprint

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We investigated the physical and chemical properties of the gas and dust components in a carbon-rich planetary nebula (PN) IC2165 using two-dimensional (2-D) emission-line maps with superior resolution. The extinction map is generated in a selfconsistent and assumption-free manner. The circumstellar gas-to-dust mass ratio (GDR) map ranges radially from 1210 in the central nebula filled with hot gas plasma to 120 near the ionisation front. The determined GDR is comparable to ∼400, which is commonly adopted for carbon-rich asymptotic giant branch (AGB) stars, and ∼100 for ISM. Except for the inner regions, the GDR in IC2165 is nearly the same as in such AGB stars, indicating that most dust grains withstand the harsh radiation field without being destroyed. The gas and dust mass distributions concentrated in the equatorial plane may be related to the nonisotropic mass loss during the AGB phase and nebula shaping. The spatial distributions of electron densities/temperatures and ionic/elemental abundances were investigated herein. We determined 13 elemental abundances using PSF-matched spatially integrated multiwavelength spectra extracted from the same aperture. Their values are consistent with values predicted by a theoretical model for stars of initially 1.75 M and 𝑍 = 0.003. Finally, we constructed the photoionisation model using our distance measurement to be consistent with all derived quantities, including the GDR and gas and dust masses and post-AGB evolution. Thus, we demonstrate the capability of Seimei/KOOLS-IFU and how the spatial variation of the gas and dust components in PNe derived from IFU observations can help understand the evolution of the circumstellar/interstellar medium.

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Akari/Irc Near-Infrared Spectral Atlas of Galactic Planetary Nebulae

Cited by 19 publications

References 55 publications

THE C–H STRETCHING FEATURES AT 3.2–3.5 μm OF POLYCYCLIC AROMATIC HYDROCARBONS WITH ALIPHATIC SIDEGROUPS

THE C–H STRETCHING FEATURES AT 3.2–3.5 μm OF POLYCYCLIC AROMATIC HYDROCARBONS WITH ALIPHATIC SIDEGROUPS

Learning mid-IR emission spectra of polycyclic aromatic hydrocarbon populations from observations

Seimei KOOLS-IFU Mapping of the Gas and Dust Distributions in Galactic Planetary Nebulae: the Case of IC2165

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