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Alinement of Solid Interstellar Particles by a Magnetic Field1

Published online by Cambridge University Press:  08 February 2017

Lyman Spitzer Jr.  and
R. V. Jones
Lyman Spitzer Jr.
Affiliation:
Princeton University, Princeton, New Jersey
R. V. Jones
Affiliation:
Harvard University, Cambridge, Massachusetts

Extract

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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.

Type
Research Article
Information
International Astronomical Union Colloquium , Volume 7: Proper Motions , August 1965 , pp. 73 - 76
Copyright
Copyright © Kluwer Academic Publishers 1965

Footnotes

1

The contents of this paper were published previously in the Astrophys. J. (published by the Univ. of Chicago Press), vol. 147, 1967, p. 943.

References

1. Davis, L.; and Greenstein, J.: Polarization of Starlight by Aligned Dust Grains. Astrophys. J., vol. 114, 1951, p. 206.10.1086/145464CrossRefGoogle Scholar
2. Henry, J.: Polarization of Starlight by Ferromagnetic Particles. Astrophys. J., vol. 128, 1958, p. 497.10.1086/146566CrossRefGoogle Scholar
3. Spitzer, L.; and Tukey, J.: A Theory of Interstellar Polarization. Astrophys J., vol. 114, 1951, p. 187.10.1086/145463CrossRefGoogle Scholar
4. Cugnon, P.: Sur la Polarisation de la lumière des étoiles. Bull. Soc. Royale d. Sciences Liege, vol. 32, 1963, p. 228.Google Scholar