The authors review the history, current status, physical mechanisms, experimental methods, and applications of nonlinear magneto-optical effects in atomic vapors. They begin by describing the pioneering work of Macaluso and Corbino over a century ago on linear magneto-optical effects (in which the properties of the medium do not depend on the light power) in the vicinity of atomic resonances. These effects are then contrasted with various nonlinear magneto-optical phenomena that have been studied both theoretically and experimentally since the late 1960s. In recent years, the field of nonlinear magneto-optics has experienced a revival of interest that has led to a number of developments, including the observation of ultranarrow (1-Hz) magneto-optical resonances, applications in sensitive magnetometry, nonlinear magneto-optical tomography, and the possibility of a search for parity- and time-reversal-invariance violation in atoms.

Resonant nonlinear magneto-optical effects in atoms

Carbon, hydrogen and nitrogen in carbonaceous chondrites: abundances and isotopic compositions in bulk samples.

The compositional classification of chondrites. vi: the cr carbonaceous chondrite group

We present a model for the thermal processing of particles in shock waves typical of the solar nebula. This shock model improves on existing models in that the dissociation and recombination of H2 and the evaporation of particles are accounted for in their effects on the mass, momentum and energy fluxes. Also, besides thermal exchange with the gas and gas-drag heating, particles can be heated by absorbing the thermal radiation emitted by other particles. The flow of radiation is calculated using the equations of radiative transfer in a slab geometry. We compute the thermal histories of particles as they encounter and pass through the shock. We apply this shock model to the melting and cooling of chondrules in the solar nebula. We constrain the combinations of shock speed and gas density needed for chondrules to reach melting temperatures, and show that these are consistent with shock waves generated by gravitational instabilities in the protoplanetary disk. After their melting, cooling rates of chondrules in the range 10-1000 K h^(-1) are naturally reproduced by the shock model. Chondrules are kept warm by the reservoir of hot shocked gas, which cools only as fast as the dust grains and chondrules themselves can radiate away the gas's energy. We predict a positive correlation between the concentration of chondrules in a region and the cooling rates of chondrules in that region. This correlation is supported by the unusually high frequency of (rapidly cooled) barred chondrules among compound chondrules, which must have collided preferentially in regions of high chondrule density. We discuss these and other compelling consistencies between the meteoritic record and the shock wave model of chondrule formation.

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A model of the thermal processing of particles in solar nebula shocks: Application to the cooling rates of chondrules

Quantizing gravity with a cosmological constant

The strength of the K line of singly ionized calcium has been measured for several hundred A-type stars within a few hundred parsecs of the Sun and for the A stars in several galactic star clusters. The derived abundance of calcium varies from star to star by up to a factor of 2, and there is no correlation of abundance with the space motion of the stars.

Abstracts of Contributed Papers

https://ntrs.nasa.gov/api/citations/19740018171/downloads/19740018171.pdf

Thermomagnetic analysis of meteorites, 2. C2 chondrites

An overview is presented of magnetism in meteorites. A glossary of magnetism terminology followed by discussion of the various techniques used for magnetism studies in meteorites are included. The generalized results from use of these techniques by workers in the field are described. A brief critical analysis is offered.

/pdf/magnetism-in-meteorites-43pzg0bj0j.pdf

Magnetism in meteorites

Thermomagnetic analysis of meteorities, 2. C2 chondrites

It is proposed that a substantial fraction of the magnetite, at least, resulted from the oxidation of troilite. Pyrrhotite is expected as a direct consequence of magnetite formation through this reaction. During thermomagnetic experiments on troilite, magnetite formation was observed at temperatures as low as 373 K, provided that the oxygen fugacity was held in the magnetite stability field, and that the troilite was sufficiently finely divided.

J. M. Herndon

Papers

Abstracts of Contributed Papers

Thermomagnetic analysis of meteorites, 2. C2 chondrites

Magnetism in meteorites

Thermomagnetic analysis of meteorities, 2. C2 chondrites

Origin of magnetite and pyrrhotite in carbonaceous chondrites