On the contribution of grain surface reactions to interstellar molecule densities

1976 ◽  
Vol 44 (2) ◽  
pp. 385-388 ◽  
Author(s):  
M. A. Leitch-Devlin ◽  
T. J. Millar ◽  
J. Pickles ◽  
D. A. Williams
Keyword(s):  
Surface Reactions ◽  
Interstellar Molecule ◽  
Grain Surface

scholarly journals Grain-surface reactions in molecular clouds: the effect of cosmic rays and quantum tunnelling

2014 ◽  
Vol 440 (4) ◽  
pp. 3557-3567 ◽  
Author(s):  
L. Reboussin ◽  
V. Wakelam ◽  
S. Guilloteau ◽  
F. Hersant
Keyword(s):  
Cosmic Rays ◽  
Molecular Clouds ◽  
Surface Reactions ◽  
Quantum Tunnelling ◽  
Grain Surface

scholarly journals Surface Reactions in Interstellar Space

2002 ◽  
Vol 12 ◽  
pp. 55-57 ◽  
Author(s):  
Eric Herbst
Keyword(s):  
Surface Chemistry ◽  
Gas Phase ◽  
Condensed Phase ◽  
Current Knowledge ◽  
Surface Reactions ◽  
Future Research ◽  
Interstellar Space ◽  
Interstellar Molecules ◽  
Grain Surface

AbstractIt is impossible to explain the abundances of some gas-phase and most condensed-phase interstellar molecules without the use of grain chemistry. Nevertheless, grain-surface chemistry is relatively poorly understood for a variety of reasons. Our current knowledge of this chemistry and its use in interstellar models is discussed along with specific needs for future research.

scholarly journals Molecular evolution in star-forming cores: From prestellar cores to protostellar cores

2008 ◽  
Vol 4 (S251) ◽  
pp. 129-136 ◽  
Author(s):  
Yuri Aikawa ◽  
Valentine Wakelam ◽  
Nami Sakai ◽  
R. T. Garrod ◽  
E. Herbst ◽  
...  
Keyword(s):  
Gas Phase ◽  
Surface Reactions ◽  
Reaction Network ◽  
Central Star ◽  
Carbon Chain ◽  
Complex Species ◽  
Star Forming ◽  
Organic Species ◽  
Molecular Abundances ◽  
Grain Surface

AbstractWe investigate the molecular abundances in protostellar cores by solving the gas-grain chemical reaction network. As a physical model of the core, we adopt a result of one-dimensional radiation-hydrodynamics calculation, which follows the contraction of an initially hydrostatic prestellar core to form a protostellar core. Temporal variation of molecular abundances is solved in multiple infalling shells, which enable us to investigate the spatial distribution of molecules in the evolving core. The shells pass through the warm region of T ~ 20–100 K in several 104 yr and falls onto the central star in ~100 yr after they enter the region of T > 100 K. We found that the complex organic species such as HCOOCH3 are formed mainly via grain-surface reactions at T ~ 20–40 K, and then sublimated to the gas phase when the shell temperature reaches their sublimation temperatures (T ≥ 100 K). Carbon-chain species can be re-generated from sublimated CH4 via gas-phase and grain-surface reactions. HCO2+, which is recently detected towards L1527, are abundant at r = 100–2,000 AU, and its column density reaches ~1011 cm−2 in our model. If a core is isolated and irradiated directly by interstellar UV radiation, photo-dissociation of water ice produces OH, which reacts with CO to form CO2 efficiently. Complex species then become less abundant compared with the case of embedded core in ambient clouds. Although a circumstellar (protoplanetary) disk is not included in our core model, we can expect similar chemical reactions (i.e., production of large organic species, carbon-chains and HCO2+) to proceed in disk regions with T ~ 20–100 K.

Molecular Evolution in Collapsing Prestellar Cores. II. The Effect of Grain‐Surface Reactions

2003 ◽  
Vol 593 (2) ◽  
pp. 906-924 ◽  
Author(s):  
Yuri Aikawa ◽  
Nagayoshi Ohashi ◽  
Eric Herbst
Keyword(s):  
Molecular Evolution ◽  
Surface Reactions ◽  
Prestellar Cores ◽  
Grain Surface

scholarly journals Mapping observations of complex organic molecules around Sagittarius B2 with the ARO 12 m telescope

2020 ◽  
Vol 492 (1) ◽  
pp. 556-565
Author(s):  
Juan Li ◽  
Junzhi Wang ◽  
Haihua Qiao ◽  
Donghui Quan ◽  
Min Fang ◽  
...  
Keyword(s):  
Spatial Distribution ◽  
Gas Phase ◽  
Low Temperatures ◽  
Organic Molecules ◽  
Methyl Formate ◽  
Surface Reactions ◽  
High Sensitivity ◽  
Methyl Amine ◽  
Grain Surface ◽  
Complex Organic

ABSTRACT We have performed high-sensitivity mapping observations of several complex organic molecules around Sagittarius B2 with the ARO 12 m telescope at 3 mm wavelength. Based on their spatial distribution, molecules can be classified as either ‘extended’, those detected not only in Sgr B2(N) and Sgr B2(M), or ‘compact’, those only detected toward or near Sgr B2(N) and Sgr B2(M). The ‘extended’ molecules include glycolaldehyde (CH2OHCHO), methyl formate (CH3OCHO), formic acid (t-HCOOH), ethanol (C2H5OH) and methyl amine (CH3NH2), while the ‘compact’ molecules include dimethyl ether (CH3OCH3), ethyl cyanide (C2H5CN), and amino acetonitrile (H2NCH2CN). These ‘compact’ molecules are likely produced under strong UV radiation, while the ‘extended’ molecules are likely formed at low temperatures, via gas-phase or grain-surface reactions. The spatial distribution of ‘warm’ CH2OHCHO at 89 GHz differs from the spatial distribution of ‘cold’ CH2OHCHO observed at 13 GHz. We found evidence for an overabundance of CH2OHCHO compared to that expected from the gas-phase model, which indicates that grain-surface reactions are necessary to explain the origin of CH2OHCHO in Sagittarius B2. Grain-surface reactions are also needed to explain the correlation between the abundances of ‘cold’ CH2OHCHO and C2H5OH. These results demonstrate the importance of grain-surface chemistry in the production of complex organic molecules.

scholarly journals Chemical Characteristics of Embedded Young Stellar Objects

2000 ◽  
Vol 197 ◽  
pp. 71-80
Author(s):  
Michiel R. Hogerheijde
Keyword(s):  
Gas Phase ◽  
Surface Reactions ◽  
Young Stellar Objects ◽  
Chemical Characteristics ◽  
Dust Grains ◽  
Gas Phase Reactions ◽  
Stellar Objects ◽  
Grain Surface ◽  
Theoretical Considerations

Based on theoretical considerations, the chemistry around embedded young stellar objects is expected to be governed by the interplay between gas-phase reactions, condensation of molecules onto dust grains, grain surface reactions, and evaporation of altered ice mantles near the star and in the outflow. I discuss the chemical characteristics of embedded young stellar objects, with special emphasis on these processes.

scholarly journals Graphite grain surface reactions in interstellar and protostellar environments

1977 ◽  
Vol 215 ◽  
pp. 800 ◽  
Author(s):  
M. J. Barlow ◽  
J. Silk
Keyword(s):  
Surface Reactions ◽  
Grain Surface

Cell parameters refinements showing an influence of the chemical nature of the grain surface on the crystalline characteristics of fine grained powders

1998 ◽  
Vol 08 (PR5) ◽  
pp. Pr5-85-Pr5-89
Author(s):  
P. Sarrazin ◽  
F. Bernard ◽  
G. Calvarin ◽  
J. C. Niepce ◽  
B. Thierry
Keyword(s):  
Chemical Nature ◽  
Cell Parameters ◽  
Fine Grained ◽  
Grain Surface
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