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Comment: 20 pages, 12 figures, Submitted in Astronomy Reports, 2010, 54, No. 12
In Montgomery (2009a), we show that accretion discs in binary systems could retrogradely precess by tidal torques like the Moon and the Sun on a tilted, spinning, non-spherical Earth. In addition, we show that the state of matter and the geometrical shape of the celestial object could significantly affect the precessional value. For example, a Cataclysmic Variable (CV) Dwarf Novae (DN) non-magnetic system that shows negative superhumps in its light curve can be described by a retrogradely precessing, differentially rotating, tilted disc. Because the disc is a fluid and because the gas stream overflows the tilted disc and particles can migrate into inner disc annuli, coupled to the disc could be a retrogradely precessing inner ring that is located near the innermost annuli of the disc. However, numerical simulations by Bisikalo et al....
Comment: 19 pages, 5 figures. Accepted for publication in Astronomy Reports
Comment: 5 pages, 2 figures; to be published in MNRAS Letters
The role of the auroral sources induced by the electron and proton precipitation in the formation of the hot oxygen corona in the polar upper atmosphere is studied. It is found that both electron precipitation through exothermic chemistry and proton precipitation through atmospheric sputtering significantly contribute to the population of the hot oxygen geocorona. It is also found that only atmospheric sputtering results in the formation of the escape flux of energetic oxygen atoms, providing an important source of heavy atoms for the magnetosphere. The exothermic chemistry induced by the electron precipitation and/or by the absorption of the solar UV radiation is operating continuously in the polar upper atmosphere and results in a steady population of the very near-Earth environment by suprathermal oxygen atoms with energies below a ...
The variation of the nitric oxide peak density near 110 km with solar activity is calculated using a photochemical diffusive model of thermospheric odd nitrogen. This model includes the reaction of translationally excited ('hot') nitrogen atoms with O2 as a source of nitric oxide, in addition to the classical photochemistry. It is confirmed that the dissociation of N2 by energetic photoelectrons due to the ionization of atmospheric constituents by solar soft X-rays is an important source of atomic nitrogen which controls the observed NO maximum near 110 km. The consideration of the hot N(4S) source increases the NO peak density by 45 to 60 percent dependent on the solar activity level considered. The calculated NO peak density increases by a factor of about 3.5 from low to high solar activity conditions, in agreement with the Solar Mes...
A nonequilibrium model to calculate the Maxwellian 'hot' N(4S) atom population using a Monte Carlo method is developed, and the NO vertical distribution for minimum solar cycle conditions is calculated. It is shown that the energetic photoelectrons produced by solar soft X-rays produce translationally 'hot' N(4S) atoms near 110 km which contribute significantly to the formation of the E-region NO peak observed at this altitude. Consideration of this new source of nitric oxide reconciles the need for an effective N(2D) quantum yield from N2 dissociation exceeding 50 percent derived from odd nitrogen models with the limits put on this value by laboratory and theoretical constraints. The altitude of the modeled NO peak is found to critically depend on the adopted N(2D) yield, and good agreement with the observed peak altitude and density ...
A model for the oxygen geocorona near the exobase solving the nonlinear Boltzmann equation with a Monte Carlo method is used to calculate the distribution of the hot oxygen atoms during geomagnetically disturbed nighttime conditions. The precipitation of energetic O(+) ions and the subsequent enhancement of the hot O corona at high latitudes is simulated for the September 17, 1971, storm conditions. It is found that in such circumstances, the O(+) precipitation is a significant source of superthermal O atoms leading to important perturbations of the velocity distribution of the bulk oxygen population. The effective gas temperature near the exobase is similar to that in the undisturbed atmosphere, but the hot O density rises considerably over the quiet condition values.
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