4,192 research outputs found
Nonequilibrium density matrix for simultaneous heat and charge steady-state transport in quantum open systems
We suggest a generalisation of the expression of the nonequilibrium density
matrix obtained by Hershfield's method for the cases where both heat and charge
steady state currents are present in a quantum open system. The finite-size
quantum system, connected to two temperature and particle reservoirs, is driven
out of equilibrium by the presence of both a temperature gradient and a
chemical potential gradient between the two reservoirs. We show that the NE
density matrix is given by a generalised Gibbs-like ensemble, and is in full
agreement with the general results of the McLennan-Zubarev nonequilibrium
ensembles. The extra non-equilibrium terms are related to the entropy
production in the system and characterise the fluxes of heat and particle.An
explicit example, for the lowest order expansion, is provide for a model system
of non-interacting fermions.Comment: accepted (Dec 2014) for publication in PR
X-ray accretion signatures in the close CTTS binary V4046 Sgr
We present Chandra HETGS observations of the classical T Tauri star (CTTS)
V4046 Sgr. The He-like triplets of O VII, Ne IX, and Si XIII are clearly
detected. Similar to the CTTS TW Hya and BP Tau, the forbidden lines of O VII
and Ne IX are weak compared to the intercombination line, indicating high
plasma densities in the X-ray emitting regions. The Si XIII triplet, however,
is within the low-density limit, in agreement with the predictions of the
accretion funnel infall model with an additional stellar corona. V4046 Sgr is
the first close binary exhibiting these features. Together with previous
high-resolution X-ray data on TW Hya and BP Tau, and in contrast to T Tau, now
three out of four CTTS show evidence of accretion funnels.Comment: 5 pages, 5 figure
The complex magnetic field of Jupiter
An analysis of the characteristics of the magnetic field of the planet Jupiter is presented. The data were obtained during the flight of Pioneer 11 space probe, using a high field triaxial fluxgate magnetometer. The data are analyzed in terms of traditional Schmitt normalized spherical harmonic expansion fitted to the observations in a least squares sense. Tables of data and graphs are provided to summarize the findings
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