The ion chemistry of interstellar clouds

1992 ◽  
Vol 92 (7) ◽  
pp. 1473-1485 ◽  
Author(s):  
David Smith
Keyword(s):  
Ion Chemistry ◽  
Interstellar Clouds

Interstellar molecules

1987 ◽  
Vol 323 (1572) ◽  
pp. 269-286 ◽  
Keyword(s):  
Molecular Species ◽  
Cometary Nucleus ◽  
Ion Chemistry ◽  
Interstellar Molecules ◽  
Interstellar Clouds ◽  
Gas Phase Ion Chemistry ◽  
Circumstellar Shells ◽  
Rare Isotopes ◽  
Diffuse Clouds ◽  
Physical And Chemical

Some 70 different molecular species have so far been detected variously in diffuse interstellar clouds, dense interstellar clouds and circumstellar shells. Only simple (diatomic and triatomic) species exist in diffuse clouds because of the penetration of destructive ultraviolet radiations, whereas more complex (polyatomic) molecules survive in dense clouds as a result of the shielding against this ultraviolet radiation provided by dust grains. A current list of interstellar molecules is given together with a few other molecular species that have so far been detected only in circumstellar shells. Also listed are those interstellar species that contain rare isotopes of several elements. The gas phase ion chemistry is outlined via which the observed molecules are synthesized, and the process by which enrichment of the rare isotopes occurs in some interstellar molecules is described. Reference is also made briefly to some very recent work in interstellar ion chemistry. A list of the atomic and molecular species that have been detected in cometary atmospheres is given and attention is drawn to the similarities and differences between interstellar and cometary molecules. The physical and chemical processes by which these observed cometary species may be generated from material that sublimes from the cometary nucleus are discussed.

scholarly journals The ion chemistry of Formula in dense interstellar clouds: an experimental study

1993 ◽  
Vol 264 (4) ◽  
pp. 862-864 ◽  
Author(s):  
S. Petrie ◽  
R. P. A. Bettens ◽  
C. G. Freeman ◽  
M. J. McEwan
Keyword(s):  
Experimental Study ◽  
Ion Chemistry ◽  
Interstellar Clouds

Dynamics of comets in the collapsing protosolar nebula

1999 ◽  
Vol 173 ◽  
pp. 45-50
Author(s):  
L. Neslušan
Keyword(s):  
Solar System ◽  
Velocity Distribution ◽  
Oort Cloud ◽  
Interstellar Clouds ◽  
Protosolar Nebula ◽  
Moving Bodies

AbstractComets are created in the cool, dense regions of interstellar clouds. These macroscopic bodies take place in the collapse of protostar cloud as mechanically moving bodies in contrast to the gas and miscroscopic dust holding the laws of hydrodynamics. In the presented contribution, there is given an evidence concerning the Solar system comets: if the velocity distribution of comets before the collapse was similar to that in the Oort cloud at the present, then the comets remained at large cloud-centric distances. Hence, the comets in the solar Oort cloud represent a relict of the nebular stage of the Solar system.

Modelling polarized radiation from interstellar clouds

2008 ◽  
Vol 31 ◽  
pp. 179-180
Author(s):  
M. Juvela ◽  
J. Goncalves ◽  
V.-M. Pelkonen ◽  
T. Lunttila
Keyword(s):  
Interstellar Clouds ◽  
Polarized Radiation

RAPID CHANGES IN MAJOR ION CHEMISTRY OF SEAWATER AND THE END-PERMIAN MASS EXTINCTION

2017 ◽  
Author(s):  
Tim K. Lowenstein ◽  
◽  
Javier Garcia Veigas ◽  
Dioni I. Cendón ◽  
Lluís Gibert Beotas
Keyword(s):  
Mass Extinction ◽  
Ion Chemistry ◽  
Major Ion Chemistry ◽  
Major Ion ◽  
Rapid Changes ◽  
Permian Mass Extinction

Preliminary Observations of Interstellar Sodium D-Line Absorption towards the Carina Nebula

1980 ◽  
Vol 4 (1) ◽  
pp. 95-97 ◽  
Author(s):  
J. B. Whiteoak ◽  
F. F. Gardner
Keyword(s):  
High Resolution ◽  
Hii Regions ◽  
Early Type ◽  
Interstellar Clouds ◽  
Carina Nebula ◽  
Line Absorption ◽  
General Investigation ◽  
Early Type Stars ◽  
Resolution Study

As part of a general investigation of interstellar clouds associated with southern HII regions we have begun a high-resolution study of the sodium D-line absorption in the directions of early-type stars that are likely to be associated with or located behind the clouds.

scholarly journals Insights into the physics when modelling cold gas clouds in a hot plasma

2019 ◽  
Vol 490 (1) ◽  
pp. L52-L56
Author(s):  
Bastian Sander ◽  
Gerhard Hensler
Keyword(s):  
Adaptive Mesh Refinement ◽  
Adaptive Mesh ◽  
Careful Consideration ◽  
Necessary Condition ◽  
Interstellar Clouds ◽  
Hot Plasma ◽  
Magnetic Dipole Field ◽  
Set Up ◽  
Self Gravity ◽  
Cold Gas

ABSTRACT This paper aims at studying the reliability of a few frequently raised, but not proven, arguments for the modelling of cold gas clouds embedded in or moving through a hot plasma and at sensitizing modellers to a more careful consideration of unavoidable acting physical processes and their relevance. At first, by numerical simulations we demonstrate the growing effect of self-gravity on interstellar clouds and, by this, moreover argue against their initial set-up as homogeneous. We apply the adaptive-mesh refinement code flash with extensions to metal-dependent radiative cooling and external heating of the gas, self-gravity, mass diffusion, and semi-analytic dissociation of molecules, and ionization of atoms. We show that the criterion of Jeans mass or Bonnor–Ebert mass, respectively, provides only a sufficient but not a necessary condition for self-gravity to be effective, because even low-mass clouds are affected on reasonable dynamical time-scales. The second part of this paper is dedicated to analytically study the reduction of heat conduction by a magnetic dipole field. We demonstrate that in this configuration, the effective heat flow, i.e. integrated over the cloud surface, is suppressed by only 32 per cent by magnetic fields in energy equipartition and still insignificantly for even higher field strengths.

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