88. The Solid Particles of Interstellar Space

1979 ◽  
pp. 605-612
Keyword(s):  
Solid Particles ◽  
Interstellar Space

scholarly journals Alinement of Solid Interstellar Particles by a Magnetic Field

1965 ◽  
Vol 7 ◽  
pp. 73-76
Author(s):  
Lyman Spitzer ◽  
R. V. Jones
Keyword(s):  
Magnetic Field ◽  
Basic Mechanism ◽  
Thermal Fluctuations ◽  
Solid Particles ◽  
Large Field ◽  
Interstellar Space ◽  
Interstellar Grains ◽  
Long Time ◽  
Satisfactory State ◽  
The Magnetic Field

For a Long Time the Davis-Greenstein Theory (ref. 1) has been generally considered an adequate explanation of the mechanism responsible for the alinement of interstellar grains and thus for the observed interstellar polarization. The magnetic field required to orient paramagnetic grains is apparently somewhat greater than 10-5 gauss, a relatively large field, but according to reference 2 ferromagnetic grains, proposed by the authors of reference 3, can be oriented by a field of only 10-7 gauss. These results indicate that orientation of interstellar grains is easily explained, even if the magnetic field in interstellar space is relatively weak.Unfortunately, this relatively satisfactory state of affairs has been upset by two developments. Firstly, the basic mechanism of magnetic relaxation proposed by Davis and Greenstein has been questioned by Dr. C. Kittel of the University of California, who has pointed out that the disorienting effect associated with thermal fluctuations of magnetization within the solid particles is ignored in the formulation of this mechanism.

scholarly journals Commission 22: Meteors, Meteorites & Interplanetary Dust

2005 ◽  
Vol 1 (T26A) ◽  
pp. 167-170
Author(s):  
Ingrid Mann ◽  
Pavel Spurný ◽  
Jack Baggaley ◽  
Jiří Borovička ◽  
Pavel Spurný ◽  
...  
Keyword(s):  
Solar System ◽  
High Performance ◽  
Leading Edge ◽  
Interplanetary Dust ◽  
Research Area ◽  
Solid Particles ◽  
Interstellar Space ◽  
Comprehensive Overview ◽  
Model Calculations ◽  
Area Of Interest

There have been three international meetings where the subject area of the meeting was to significant extent within the area of interest of commission 22. These were: The Meteoroids 2004 Conference was held at the University of Western Ontario in London, Canada from August 15 to 21, 2004. This conference was the fifth in a series of meteoroid meetings which have been held approximately every three years since 1992, the previous one being in Kiruna, Sweden in 2001. Ingrid Mann chaired a scientific organizing committee which set the program for the conference. The meeting brought together scientists from more than twenty countries, to deliver 84 oral and 38 poster presentations. The papers represented the research contributions of more than 150 different scientists. The conference provided a comprehensive overview of leading edge research on topics ranging from the dynamics, sources and distribution of meteoroids, their chemistry and their physical processes in the interplanetary medium and the Earthõs atmosphere, and space and laboratory studies of meteorites, micrometeorites and interplanetary dust were also well represented. It was clear from the conference that the coordinated international campaigns for the Leonid showers provided a rich observational dataset and lead to the development of new observational and analysis techniques. Another trend obvious at the conference was the increasing use of sophisticated large aperture radars for meteor studies. High performance computing facilitates both dynamical model calculations and sophisticated ablation models. Significant progress was reported on ablation models for meteoroids ranging from dust to those producing bright fireballs. Study of solid particles entering the solar system from interstellar space and improved dust measuring capabilities on interplanetary spacecraft are an important research area which links astrophysical dust with solar system dust. The majority of papers presented at the conference (a total of 69 papers) are being published as a special issue of the journal Earth, Moon, and Planets (Vol. 95, Nos. 1–4) and also in the form of an associated book published by Springer: Modern Meteor Science: An Interdisciplinary View which was edited by R.Hawkes, I. Mann and P. Brown (ISBN 1-4020-4374-0). The book will be accompanied by a CD-ROM which includes a selection of conference photographs and the complete abstracts of all papers from the conference. As is reflected in the title of the spin-off book, this field is becoming increasingly interdisciplinary in nature, with researchers from astronomy, astrophysics, space science, space engineering, cosmochemistry, atmospheric science and geophysics, as well as others, now contributing to research in the field.

Light Scattering in Reflection Nebulae

1970 ◽  
Vol 1 (7) ◽  
pp. 330-332
Author(s):  
I. R. Shortt
Keyword(s):  
Optical Properties ◽  
Light Scattering ◽  
Broad Band ◽  
Solid Particles ◽  
Line Of Sight ◽  
Interstellar Space ◽  
Small Particles ◽  
Scattering Of Light ◽  
Stellar Radiation ◽  
Reflection Nebulae

Much of the information regarding the nature of solid particles in interstellar space has been gained through the study of the line-of-sight extinction of starlight and the polarization of starlight by these particles. Study of the optical properties of these particles can be extended through consideration of the scattering of stellar radiation in reflection nebulae. This type of approach requires the adoption of models for the star-nebula system, and the grain type to be considered. These models are then used in a theory which describes the scattering of light by an ensemble of small particles, as applied to dust nebulae. Results are thus obtained for the colour of the nebula as a function of distance from the illuminating star. These results can then be compared with the corresponding results of experimental broad-band photometry.

scholarly journals The Physics of the Interstellar Matter

1974 ◽  
Vol 3 ◽  
pp. 37-49 ◽  
Author(s):  
G. B. Field
Keyword(s):  
Solar System ◽  
Interstellar Medium ◽  
The United States ◽  
Astronomical Observatory ◽  
Solid Particles ◽  
Heavy Elements ◽  
Interstellar Space ◽  
Interstellar Matter ◽  
Hydrogen Molecules ◽  
Long Time

Some of the most striking recent discoveries about interstellar matter involve molecules. It has been known for a long time that there are atoms and ions in space - mainly hydrogen and helium, of course - but also heavier elements like sodium and calcium. In addition, there are solid particles of dust, about 10-5cm across, which must be composed of heavier elements, as hydrogen and helium cannot condense under interstellar conditions.In 1972, the Orbiting Astronomical Observatory-3, which employs an 80-cm telescope at wavelengths between 1000Å and 3000Å, was launched in the United States and put into operation. In the ensuing year, it has demonstrated that much of the interstellar medium is composed of hydrogen molecules. This result, based upon the observation of Lyman-band absorption in the spectrum of early-type stars, had been anticipated by a rocket observation of H2 by Carruthers in 1970.The same OAO-3 instrument observed resonance lines of many cosmically abundant elements, and found that these elements often appear to be less abundant in interstellar space than in the solar system, relative to hydrogen. As young stars born recently from the interstellar medium do not show this effect, the heavy elements must in fact be present in some other form. Here I will argue that the heavy elements are largely locked up in the form of the dust and, further, that dust is critical for the formation of the molecules in interstellar space.It is appropriate that the Orbiting Astronomical Observatory-3 which made these discoveries has been named in honor of Copernicus, the Polish astronomer we honor here on the 500th anniversary of his birth. Just as his discoveries were revolutionary for the understanding of the solar system, those made using the Observatory named in his honor have been revolutionary for the understanding of the Galaxy.

Abrasive wear of polymer/steel gear drives

2008 ◽  
Vol 4 (1) ◽  
pp. 1-26
Author(s):  
Gábor Kalácska
Keyword(s):  
Wear Resistance ◽  
Abrasive Wear ◽  
Material Selection ◽  
Solid Particles ◽  
Soil Types ◽  
General View ◽  
Modern Engineering ◽  
Clean Environment ◽  
Engineering Polymers ◽  
Plastic Gears

Research was performed on the friction, wear and efficiency of plastic gears made of modern engineering polymers and their composites both in a clean environment (adhesive sliding surfaces) and in an environment contaminated with solid particles and dust (abrasive), with no lubrication at all. The purpose is to give a general view about the results of abrasive wear tests including seven soil types as abrasive media. At the first stage of the research silicious sand was applied between the meshing gears and the wear of plastic and steel gears was evaluated and analyzed from the point of different material properties (elongation at break, hardness, yield stress, modulus of elasticity) and its combinations. The different correlations between the experienced wear and material features are also introduced. At the second stage of the project the abrasive sand was replaced with different physical soil types. The abrasive wear of gears is plotted in the function of soil types. The results highlight on the considerable role of physical soil types on abrasive wear resistance and the conclusions contain the detailed wear resistance. The results offer a new tribology database for the operation and maintenance of agricultural machines with the opportunity of a better material selection according to the dominant soil type. This can finally result longer lifetime and higher reliability of wearing plastic/steel parts.

INVERSE PROBLEMS METHOD FOR STUDY OF HEAT TRANSFER IN SOLIDS INTERACTED WITH GAS FLOWS LOADED BY SOLID PARTICLES

Equipment ◽  
2006 ◽  
Author(s):  
Aleksey V. Nenarokomov ◽  
O. M. Alifanov ◽  
E. A. Artioukhine ◽  
I. V. Repin
Keyword(s):  
Heat Transfer ◽  
Inverse Problems ◽  
Solid Particles ◽  
Gas Flows

Flow and Heat Transfer Within Segregated Beds of Solid Particles

2001 ◽  
Vol 4 (3) ◽  
pp. 10 ◽  
Author(s):  
Abdulmajeed A. Mohamad ◽  
G. A. Karim
Keyword(s):  
Heat Transfer ◽  
Solid Particles ◽  
Flow And Heat Transfer
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