Ionized polycyclic aromatic hydrocarbons and the diffuse interstellar bands

Crawford, M. K.; Tielens, A. G. G. M.; Allamandola, Louis J.

doi:10.1086/184488

Cited by 193 publications

(102 citation statements)

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“…A DIB radial gradient was established for the first time in a 160 Mpc distant galaxy (Monreal-Ibero et al 2015). Carbon is involved in most of the proposed candidates for DIB carriers in the form of hydrocarbon chains (e.g., Maier et al 2004), polycyclic aromatic hydrocarbons (PAHs, e.g., van der Zwet & Allamandola 1985; Leger & D'Hendecourt 1985;Crawford et al 1985;Salama et al 1996;Kokkin et al 2008), and/or fullerenes (Iglesias-Groth 2007; Sassara et al 2001). Recent reviews about the DIB-PAH and the fullerene hypotheses can be found in Cox (2011);Omont (2016).…”

Section: Introductionmentioning

confidence: 99%

Near-infrared diffuse interstellar bands in APOGEE telluric standard star spectra

Elyajouri

Lallement

Monreal-Ibero

et al. 2017

A&A

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Aims. Information on the existence and properties of diffuse interstellar bands (DIBs) outside the optical domain is still limited. Additional infra-red (IR) measurements and IR-optical correlative studies are needed to constrain DIB carriers and locate various absorbers in 3D maps of the interstellar matter. Methods. We extended our study of H-band DIBs in Apache Point Observatory Galactic Evolution Experiment (APOGEE) Telluric Standard Star (TSS) spectra. We used the strong λ15273 band to select the most and least absorbed targets. We used individual spectra of the former subsample to extract weaker DIBs, and we searched the two stacked series for differences that could indicate additional bands. High-resolution NARVAL and SOPHIE optical spectra for a subsample of 55 TSS targets were additionally recorded for NIR/optical correlative studies. Results. From the TSS spectra we extract a catalog of measurements of the poorly studied λλ15617, 15653, and 15673 DIBs in 300 sightlines, we obtain a first accurate determination of their rest wavelength and constrained their intrinsic width and shape. In addition, we studied the relationship between these weak bands and the strong λ15273 DIB. We provide a first or second confirmation of several other weak DIBs that have been proposed based on different instruments, and we add new constraints on their widths and locations. We finally propose two new DIB candidates. Conclusions. We compared the strength of the λ15273 absorptions with their optical counterparts λλ5780, 5797, 6196, 6283, and 6614. Using the 5797-5780 ratio as a tracer of shielding against the radiation field, we showed that the λ15273 DIB carrier is significantly more abundant in unshielded (σ-type) clouds, and it responds even more strongly than the λ5780 band carrier to the local ionizing field.

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Section: Introductionmentioning

confidence: 99%

Near-infrared diffuse interstellar bands in APOGEE telluric standard star spectra

Elyajouri

Lallement

Monreal-Ibero

et al. 2017

A&A

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“…Although spectral features in the visible to UV range of wavelengths are observed and carried by carbonaceous materials (Désert et al 1990;Draine 2003;Zubko et al 2004), this fraction of cosmic dust is mainly observed through remote infrared (IR) spectroscopy. In particular, the mid-IR emission features observed in many astronomical objects (Gillett et al 1973), often called the aromatic infrared bands (AIBs), trace carbonaceous particles of a few nanometers often attributed to PAHs in most of the astrophysical literature (Léger & Puget 1984;Crawford et al 1985;Tielens 2008). Heated by UV and visible starlight, these nanoparticles emit through their vibrational bands thanks to an out-of-equilibrium process known as the transient heating mechanism (Puget & Léger 1989;Allamandola et al 1989;Draine & Li 2001).…”

Section: Introductionmentioning

confidence: 99%

Nanostructuration of carbonaceous dust as seen through the positions of the 6.2 and 7.7μm AIBs

Carpentier

Féraud

Dartois

et al. 2012

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“…[20] Indeed, observations are beginning to support this picture. [28] Others suggested that PAHs could fundamentally influence temperature [29,30], and ionization level, chemistry, and radiative transfer [31] within molecular clouds, thereby influencing star formation; that interstellar PAHs may have been the source of much of the carbon in meteorites and interplanetary dust particles [32][33][34][35]; and that PAHs in one form or another might account for some of the enigmatic visible/near-IR diffuse interstellar bands (DIBs) [36][37][38], a very long-standing interstellar puzzle. Comprehensive discussions of the PAH model as it stood at the end of the 1980's can be found in the literature [39,40] and a more thorough discussion of the widespread evidence for PAHs can be found in reference [41].…”

Section: Interstellar Pahs: the Observational Foundationmentioning

confidence: 99%

From Interstellar Polycyclic Aromatic Hydrocarbons and Ice to Astrobiology

Allamandola

Hudgins

2003

Solid State Astrochemistry

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Tremendous strides have been made in our understanding of interstellar material over the past twenty years thanks to significant, parallel developments in observational astronomy and laboratory astrophysics. Twenty years ago the composition of interstellar dust was largely guessed at, the concept of ices in dense molecular clouds ignored, and the notion of large, abundant, gas phase, carbon rich molecules widespread throughout the interstellar medium (ISM) considered impossible.Today the composition of dust in the diffuse ISM is reasonably well constrained to micron-sized cold refractory materials comprised of amorphous and crystalline silicates mixed with an amorphous carbonaceous material containing aromatic structural units and short, branched aliphatic chains. In dense molecular clouds, the birthplace of stars and planets, these cold dust particles are coated with mixed molecular ices whose major components are is very well constrained. Lastly, the signature of carbon-rich polycyclic aromatic hydrocarbons (PAHs), shockingly large molecules by earlier interstellar chemistry standards, is widespread throughout the Universe. This paper presents a detailed summary of these disparate interstellar components and ends by considering both of them as important feedstock to the chemical inventory of the primordial Earth. Particular attention is paid to their possible role in the chemistry that led to the origin of life. An extensive reference list is given to allow the student entry into the full depth of the literature.The first part of this paper focuses on interstellar PAHs. The laboratory and theoretical underpinning which supports the PAH model is reviewed in some detail. This is followed by a few specific examples which demonstrate how these data can be used to analyze the interstellar spectra and probe local conditions in different emission zones. These examples include tracing the evolution of carbon as it passes from its birthsite in circumstellar shells through the ISM, determining specifics about the cosmic PAH population in many different environments including PAH size and structure, and probing local conditions in the different emission zones.The second part of this paper summarizes the laboratory and observational background leading to our current understanding of interstellar/precometary ices. Although the most abundant interstellar ice components are the very simple molecules such as H 2 O, CH 3 OH, CO, CO 2 , and NH 3 , more complex species including accreted PAHs and those formed by UV and cosmic ray processing within the ice must also be present. Here we give a detailed summary of the photochemical evolution on those ices 2 found in the densest regions of molecular clouds, the regions where stars and planetary systems are formed. Ultraviolet photolysis of these ices produces a host of new compounds, some of which show intriguing prebiotic behavior.The last part of this paper draws all this information together and considers the possible roles these compounds might have played in early Earth...

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Ionized polycyclic aromatic hydrocarbons and the diffuse interstellar bands

Cited by 193 publications

References 0 publications

Near-infrared diffuse interstellar bands in APOGEE telluric standard star spectra

Near-infrared diffuse interstellar bands in APOGEE telluric standard star spectra

Nanostructuration of carbonaceous dust as seen through the positions of the 6.2 and 7.7μm AIBs

From Interstellar Polycyclic Aromatic Hydrocarbons and Ice to Astrobiology

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