Theoretical and Laboratory Studies on the Interaction of Cosmic‐Ray Particles with Interstellar Ices. III. Suprathermal Chemistry–Induced Formation of Hydrocarbon Molecules in Solid Methane (CH4), Ethylene (C2H4), and Acetylene (C2H2)

1998 ◽  
Vol 503 (2) ◽  
pp. 959-975 ◽  
Author(s):  
R. I. Kaiser ◽  
K. Roessler
Keyword(s):  
Cosmic Ray ◽  
Laboratory Studies ◽  
Hydrocarbon Molecules ◽  
Interstellar Ices ◽  
Solid Methane

scholarly journals Chemistry of Molecular Clouds

1989 ◽  
Vol 120 ◽  
pp. 2-12
Author(s):  
A. Dalgarno
Keyword(s):  
Polycyclic Aromatic Hydrocarbon ◽  
Ultraviolet Radiation ◽  
Aromatic Hydrocarbon ◽  
Molecular Clouds ◽  
Cosmic Ray ◽  
Radiation Fields ◽  
Polycyclic Aromatic ◽  
Hydrocarbon Molecules ◽  
Ultraviolet Photons

AbstractA discussion is presented of the chemistry of quiescent molecular clouds, and the effects of the presence of polycyclic aromatic hydrocarbon molecules and of cosmic-ray induced ultraviolet photons are examined. A comparison is made with the chemistry occurring in molecular clouds that are subjected to shocks and the differences between dissociative and non-dissociative shocks are described. The changes in composition caused by intense cosmic ray fluxes or intense ultraviolet radiation fields are explored.

Cosmic Ray Compaction of Porous Interstellar Ices

2008 ◽  
Vol 687 (2) ◽  
pp. 1070-1074 ◽  
Author(s):  
U. Raut ◽  
M. Famá ◽  
M. J. Loeffler ◽  
R. A. Baragiola
Keyword(s):  
Cosmic Ray ◽  
Interstellar Ices

scholarly journals A study of interstellar aldehydes and enols as tracers of a cosmic ray-driven nonequilibrium synthesis of complex organic molecules

2016 ◽  
Vol 113 (28) ◽  
pp. 7727-7732 ◽  
Author(s):  
Matthew J. Abplanalp ◽  
Samer Gozem ◽  
Anna I. Krylov ◽  
Christopher N. Shingledecker ◽  
Eric Herbst ◽  
...  
Keyword(s):  
Organic Molecules ◽  
Cosmic Ray ◽  
Formation Mechanisms ◽  
Molecular Precursors ◽  
Star Forming ◽  
Star Forming Regions ◽  
Interstellar Ices ◽  
A Chain ◽  
Nonequilibrium Chemistry ◽  
Complex Organic

Complex organic molecules such as sugars and amides are ubiquitous in star- and planet-forming regions, but their formation mechanisms have remained largely elusive until now. Here we show in a combined experimental, computational, and astrochemical modeling study that interstellar aldehydes and enols like acetaldehyde (CH3CHO) and vinyl alcohol (C2H3OH) act as key tracers of a cosmic-ray-driven nonequilibrium chemistry leading to complex organics even deep within low-temperature interstellar ices at 10 K. Our findings challenge conventional wisdom and define a hitherto poorly characterized reaction class forming complex organic molecules inside interstellar ices before their sublimation in star-forming regions such as SgrB2(N). These processes are of vital importance in initiating a chain of chemical reactions leading eventually to the molecular precursors of biorelevant molecules as planets form in their interstellar nurseries.

scholarly journals Cosmic ray impact on astrophysical ices: laboratory studies on heavy ion irradiation of methane

2011 ◽  
Vol 531 ◽  
pp. A160 ◽  
Author(s):  
A. L. F. de Barros ◽  
V. Bordalo ◽  
E. Seperuelo Duarte ◽  
E. F da Silveira ◽  
A. Domaracka ◽  
...  
Keyword(s):  
Ion Irradiation ◽  
Cosmic Ray ◽  
Heavy Ion ◽  
Laboratory Studies ◽  
Heavy Ion Irradiation ◽  
Astrophysical Ices

scholarly journals Efficient Production of S8 in Interstellar Ices: The Effects of Cosmic-Ray-driven Radiation Chemistry and Nondiffusive Bulk Reactions

2020 ◽  
Vol 888 (1) ◽  
pp. 52 ◽  
Author(s):  
Christopher N. Shingledecker ◽  
Thanja Lamberts ◽  
Jacob C. Laas ◽  
Anton Vasyunin ◽  
Eric Herbst ◽  
...  
Keyword(s):  
Cosmic Ray ◽  
Radiation Chemistry ◽  
Efficient Production ◽  
Interstellar Ices

scholarly journals Metamorphism of Cosmic Dust: Diagnostic Infrared Signatures

1992 ◽  
Vol 150 ◽  
pp. 39-40
Author(s):  
Joseph A. Nuth
Keyword(s):  
Absorption Band ◽  
Gas Phase ◽  
High Efficiency ◽  
Driving Forces ◽  
Cosmic Ray ◽  
High Energy ◽  
Laboratory Studies ◽  
Continuous Increase ◽  
Relative Age ◽  
Equilibrium Process

Nucleation is a non-equilibrium process: the products of this process are seldom the most thermodynamically stable condensates but are instead those which form fastest. It should not be surprising that grains formed in a circumstellar outflow will undergo some degree of metamorphism if they are annealed or exposed to a chemically active reagent. As a consequence of this processing in the laboratory one observes a continuous increase in the strength of the silicate absorption band at 20 microns relative to the 10 micron feature. In Section 1 we show that this ratio can be used as an indicator of the relative age of silicate condensates. Metamorphism of refractory particles continues in the interstellar medium (ISM) where the driving forces are sputtering by cosmic ray particles, annealing by high energy photons and grain destruction in supernova generated shocks. Studies of the depletion of the elements from the gas phase of the ISM tell us that if grain destruction occurs with high efficiency, then there must be some mechanism by which grains can be formed in the ISM. Laboratory studies of such a process (Moore, Tanabe, and Nuth, Ap. J. (Lett) 373, L31-L34, 1990) have shown that the frequency of the -SiH stretch can be used as an indicator of the oxidation state of the silicon in such grains. Highly reduced grains exhibit an SiH absorption near 2100 cm−1 whereas highly oxidized silicates absorb near 2300 cm−1: this point is discussed in Section 2.

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