scholarly journals Laboratory and Modeling Studies of Chemistry in Dense Molecular Clouds

1980 ◽  
Vol 87 ◽  
pp. 331-336
Author(s):  
W.T. Huntress ◽  
S. S. Prasad ◽  
G. F. Mitchell
Keyword(s):  
Chemical Equilibrium ◽  
Molecular Clouds ◽  
Evolutionary Model ◽  
Chemical Processes ◽  
Chemical Library ◽  
Interstellar Clouds ◽  
Organic Species ◽  
Radiative Association ◽  
Simple Chemical ◽  
Complex Organic

A chemical evolutionary model with a large number of species and a large chemical library is used to examine the principal chemical processes in interstellar clouds. Simple chemical equilibrium arguments show the potential for synthesis of very complex organic species by ion-molecule radiative association reactions.

Reactions

2011 ◽  
Author(s):  
Peter Atkins
Keyword(s):  
Chemical Reactions ◽  
Molecular Level ◽  
Chemical Processes ◽  
Chemical Formula ◽  
Complex Processes ◽  
Full Color ◽  
Chemistry Textbooks ◽  
Simple Chemical ◽  
The Subject ◽  
Solid Form

Illustrated with remarkable new full-color images--indeed, one or more on every page--and written by one of the world's leading authorities on the subject, Reactions offers a compact, pain-free tour of the inner workings of chemistry. Reactions begins with the chemical formula almost everyone knows--the formula for water, H2O--a molecule with an "almost laughably simple chemical composition." But Atkins shows that water is also rather miraculous--it is the only substance whose solid form is less dense than its liquid (hence ice floats in water)--and incredibly central to many chemical reactions, as it is an excellent solvent, being able to dissolve gases and many solids. Moreover, Atkins tells us that water is actually chemically aggressive, and can react with and destroy the compounds dissolved in it, and he shows us what happens at the molecular level when water turns to ice--and when it melts. Moving beyond water, Atkins slowly builds up a toolkit of basic chemical processes, including precipitation (perhaps the simplest of all chemical reactions), combustion, reduction, corrosion, electrolysis, and catalysis. He then shows how these fundamental tools can be brought together in more complex processes such as photosynthesis, radical polymerization, vision, enzyme control, and synthesis. Peter Atkins is the world-renowned author of numerous best-selling chemistry textbooks for students. In this crystal-clear, attractively illustrated, and insightful volume, he provides a fantastic introductory tour--in just a few hundred colorful and lively pages - for anyone with a passing or serious interest in chemistry.

scholarly journals AN EVOLUTIONARY MODEL FOR COLLAPSING MOLECULAR CLOUDS AND THEIR STAR FORMATION ACTIVITY

2012 ◽  
Vol 751 (1) ◽  
pp. 77 ◽  
Author(s):  
Manuel Zamora-Avilés ◽  
Enrique Vázquez-Semadeni ◽  
Pedro Colín
Keyword(s):  
Star Formation ◽  
Molecular Clouds ◽  
Evolutionary Model ◽  
Star Formation Activity

scholarly journals Observability of the Magnetic Field in Molecular Clouds

1990 ◽  
Vol 140 ◽  
pp. 304-304
Author(s):  
N. Bel ◽  
B. Leroy
Keyword(s):  
Magnetic Field ◽  
Molecular Clouds ◽  
Diatomic Molecules ◽  
Zeeman Effect ◽  
Interstellar Clouds ◽  
The Magnetic Field

We have done detailed calculations of the Zeeman effect in the dozen diatomic molecules identified in interstellar clouds.

scholarly journals The Mass Spectrum of Interstellar Clouds

1989 ◽  
Vol 120 ◽  
pp. 511-517
Author(s):  
John M. Dickey ◽  
R. W. Garwood
Keyword(s):  
Cross Sections ◽  
Molecular Clouds ◽  
Column Density ◽  
Unit Volume ◽  
Empirical Relationship ◽  
Line Of Sight ◽  
Interstellar Clouds ◽  
Absorption Studies ◽  
Low Latitudes ◽  
Diffuse Clouds

AbstractThe abundance of 21-cm absorption lines seen in surveys at high latitudes can be translated into a line of sight abundance of clouds vs. column density using an empirical relationship between temperature and optical depth. As VLA surveys of 21-cm absorption at low latitudes are now becoming available, it is possible to study the variation of this function with galactic radius. It is interesting to compare the abundance of these diffuse atomic clouds (with temperatures of 50 to 100 K and masses of 1 to 10 M⊙) to the abundance of molecular clouds. To do the latter we must make assumptions about cloud cross-sections in order to convert the line of sight abundance of diffuse clouds into a number per unit volume, and to convert from cloud column density to mass. The spectrum of diffuse clouds matches fairly well the spectrum of molecular clouds, although observationally there is a gap of several orders of magnitude in cloud mass. Optical absorption studies also agree well with the 21-cm results for clouds of column density a few times 1020 M⊙.

scholarly journals Measurements of Isotopic Abundances in Interstellar Clouds

1980 ◽  
Vol 87 ◽  
pp. 397-404 ◽  
Author(s):  
Arno A. Penzias
Keyword(s):  
Molecular Clouds ◽  
General Framework ◽  
Galactic Center ◽  
Galactic Plane ◽  
Giant Molecular Clouds ◽  
Interstellar Clouds ◽  
The Galaxy ◽  
Isotopic Abundances ◽  
Si Isotopes

While an examination of the available data reveals some seemingly contradictory results, a general framework having the following outlines can be put forward:1. With the exception of the two galactic center sources SgrA and SgrB, the relative isotopic abundances exhibited by the giant molecular clouds in our Galaxy exhibit few, if any, significant variations from the values obtained by averaging the data from all these sources.2. The 13C/12C and 14N/15N abundance ratios are ∼130% and ∼150%, respectively, of their terrestrial values throughout the galactic plane and somewhat higher, ∼300%, near the galactic center.3. The 16O/18O and 17O/18O abundance ratios are ∼130% and ∼160%, respectively, of their terrestrial values throughout the Galaxy, although the former may be somewhat lower near the galactic center.4. The S and Si isotopes have generally terrestrial abundances.

scholarly journals Aldehydes and sugars from evolved precometary ice analogs: Importance of ices in astrochemical and prebiotic evolution

2015 ◽  
Vol 112 (4) ◽  
pp. 965-970 ◽  
Author(s):  
Pierre de Marcellus ◽  
Cornelia Meinert ◽  
Iuliia Myrgorodska ◽  
Laurent Nahon ◽  
Thomas Buhse ◽  
...  
Keyword(s):  
Gas Phase ◽  
Molecular Clouds ◽  
Room Temperature ◽  
Laboratory Experiments ◽  
Organic Residue ◽  
Organic Residues ◽  
Flight Mass Spectrometry ◽  
The Earth ◽  
Planetary Environment ◽  
Complex Organic

Evolved interstellar ices observed in dense protostellar molecular clouds may arguably be considered as part of precometary materials that will later fall on primitive telluric planets, bringing a wealth of complex organic compounds. In our laboratory, experiments reproducing the photo/thermochemical evolution of these ices are routinely performed. Following previous amino acid identifications in the resulting room temperature organic residues, we have searched for a different family of molecules of potential prebiotic interest. Using multidimensional gas chromatography coupled to time-of-flight mass spectrometry, we have detected 10 aldehydes, including the sugar-related glycolaldehyde and glyceraldehyde—two species considered as key prebiotic intermediates in the first steps toward the synthesis of ribonucleotides in a planetary environment. The presence of ammonia in water and methanol ice mixtures appears essential for the recovery of these aldehydes in the refractory organic residue at room temperature, although these products are free of nitrogen. We finally point out the importance of detecting aldehydes and sugars in extraterrestrial environments, in the gas phase of hot molecular clouds, and, more importantly, in comets and in primitive meteorites that have most probably seeded the Earth with organic material as early as 4.2 billion years ago.

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