On the molecular complexity of the hot cores in Orion A - Grain surface chemistry as 'The last refuge of the scoundrel'

Charnley, Steven B.; Tielens, A. G. G. M.; Millar, T. J.

doi:10.1086/186609

Cited by 403 publications

(405 citation statements)

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“…Table 1 shows that, although there are some discrepancies, there is a strong correspondence between cometary molecules and those detected in interstellar ice mantles or in warm gas containing these evaporated ices -so-called 'hot cores' (e.g. Charnley et al 1992). We can strengthen this connection both by modelling coma organic chemistry and by exploring the implications interstellar grain chemistry theories have for cometary composition.…”

Section: Hcn In Comet Ikeya-zhangmentioning

confidence: 89%

Chemical Processes in Cometary Comae

Charnley

Rodgers

Butner

et al. 2002

Cometary Science After Hale-Bopp

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Section: Hcn In Comet Ikeya-zhangmentioning

confidence: 89%

Chemical Processes in Cometary Comae

Charnley

Rodgers

Butner

et al. 2002

Cometary Science After Hale-Bopp

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“…The presence of methanol in these ices is of pivotal importance since it drives a rich interstellar ice photochemistry [130,145,206] and plays an important role in gas phase chemistry. [207] Furthermore, methanol has profound effects on the physical behavior of H 2 O-rich ices. [208] Since CH 3 OH is often an abundant ice component in comets (Table 7, cf.…”

Section: Photochemical Evolution Of the Organic Materials In Interstelmentioning

confidence: 99%

“…Thus, the molecular inventory of cold, dark interstellar clouds must be shaped by a combination of ion-molecule reactions in the gas phase and gas-grain surface reactions (e.g. [9,10]). Moreover, the attenuated diffuse ISM UV which penetrates a dense cloud, as well as UV from internal sources and penetrating cosmic ray particles are sufficient to drive in-situ, solid-state reactions within the icy grain mantles leading to a variety of even more complex species.…”

Section: Introductionmentioning

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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“…(ii) Time-dependent, depth-independent models, in which the concentrations are computed as functions of time at a single position deep into the cloud. Models of dark pre-stellar cores (e.g., Lee et al 1996a, Millar et al 1997b, collapsing envelopes (e.g., ) and hot cores near massive young stars (e.g., Charnley et al 1992) fall into this category. The time scale for reaching chemical equilibrium depends on the density, temperature and ionization fraction and is typically 10 5 -10 7 yr.…”

Section: Gas-phase Networkmentioning

confidence: 99%

“…Charnley et al (1992) showed that the observed abundances in the Orion hot cores can be reproduced if a mixture of simple ices containing H 2 O, CO, CH 3 OH, NH 3 and/or HCN is evaporated into the warm gas. These molecules sub- Figure 12.…”

Section: Hot Core Regionsmentioning

confidence: 99%