21 research outputs found
Neutral H density at the termination shock: a consolidation of recent results
We discuss a consolidation of determinations of the density of neutral
interstellar H at the nose of the termination shock carried out with the use of
various data sets, techniques, and modeling approaches. In particular, we focus
on the determination of this density based on observations of H pickup ions on
Ulysses during its aphelion passage through the ecliptic plane. We discuss in
greater detail a novel method of determination of the density from these
measurements and review the results from its application to actual data. The H
density at TS derived from this analysis is equal to 0.087 \pm 0.022 cm-3, and
when all relevant determinations are taken into account, the consolidated
density is obtained at 0.09 \pm 0.022 cm-3. The density of H in CHISM based on
literature values of filtration factor is then calculated at 0.16 \pm 0.04
cm-3.Comment: Submitted to Space Science Review
Coulomb gap in one-dimensional disordered electronic systems
We study a one-dimensional system of spinless electrons in the presence of a
long-range Coulomb interaction (LRCI) and a random chemical potential at each
site. We first present a Tomonaga-Luttinger liquid (TLL) description of the
system. We use the bosonization technique followed by the replica trick to
average over the quenched randomness. An expression for the localization length
of the system is then obtained using the renormalization group method and also
a physical argument. We then find the density of states for different values of
the energy; we get different expressions depending on whether the energy is
larger than or smaller than the inverse of the localization length. We work in
the limit of weak disorder where the localization length is very large; at that
length scale, the LRCI has the effect of reducing the interaction parameter K
of the TLL to a value much smaller than the noninteracting value of unity.Comment: Revtex, 6 pages, no figures; discussions have been expanded in
several place
Coulomb Gaps in One-Dimensional Spin-Polarized Electron Systems
We investigate the density of states (DOS) near the Fermi energy of
one-dimensional spin-polarized electron systems in the quantum regime where the
localization length is comparable to or larger than the inter-particle
distance. The Wigner lattice gap of such a system, in the presence of weak
disorder, can occur precisely at the Fermi energy, coinciding with the Coulomb
gap in position. The interplay between the two is investigated by treating the
long-range Coulomb interaction and the random disorder potential in a
self-consistent Hartree-Fock approximation. The DOS near the Fermi energy is
found to be well described by a power law whose exponent decreases with
increasing disorder strength.Comment: 4 pages, revtex, 4 figures, to be published in Phys. Rev. B as a
Rapid Communicatio
Influence of fast interstellar gas flow on dynamics of dust grains
The orbital evolution of a dust particle under the action of a fast
interstellar gas flow is investigated. The secular time derivatives of
Keplerian orbital elements and the radial, transversal, and normal components
of the gas flow velocity vector at the pericentre of the particle's orbit are
derived. The secular time derivatives of the semi-major axis, eccentricity, and
of the radial, transversal, and normal components of the gas flow velocity
vector at the pericentre of the particle's orbit constitute a system of
equations that determines the evolution of the particle's orbit in space with
respect to the gas flow velocity vector. This system of differential equations
can be easily solved analytically. From the solution of the system we found the
evolution of the Keplerian orbital elements in the special case when the
orbital elements are determined with respect to a plane perpendicular to the
gas flow velocity vector. Transformation of the Keplerian orbital elements
determined for this special case into orbital elements determined with respect
to an arbitrary oriented plane is presented. The orbital elements of the dust
particle change periodically with a constant oscillation period or remain
constant. Planar, perpendicular and stationary solutions are discussed.
The applicability of this solution in the Solar system is also investigated.
We consider icy particles with radii from 1 to 10 micrometers. The presented
solution is valid for these particles in orbits with semi-major axes from 200
to 3000 AU and eccentricities smaller than 0.8, approximately. The oscillation
periods for these orbits range from 10^5 to 2 x 10^6 years, approximately.Comment: 22 pages, 3 figures; Accepted for publication in Celestial Mechanics
and Dynamical Astronom