123 research outputs found
Electromagnetic Effects in Superconductors in Gravitational Field
The general relativistic modifications to the resistive state in
superconductors of second type in the presence of a stationary gravitational
field are studied. Some superconducting devices that can measure the
gravitational field by its red-shift effect on the frequency of radiation are
suggested. It has been shown that by varying the orientation of a
superconductor with respect to the earth gravitational field, a corresponding
varying contribution to AC Josephson frequency would be added by gravity. A
magnetic flux (being proportional to angular velocity of rotation )
through a rotating hollow superconducting cylinder with the radial gradient of
temperature is theoretically predicted. The magnetic flux is
assumed to be produced by the azimuthal current arising from Coriolis force
effect on radial thermoelectric current. Finally the magnetic flux through the
superconducting ring with radial heat flow located at the equatorial plane
interior the rotating neutron star is calculated. In particular it has been
shown that nonvanishing magnetic flux will be generated due to the general
relativistic effect of dragging of inertial frames on the thermoelectric
current.Comment: 11 pages 2 figure
General Relativistic Magnetospheres of Slowly Rotating and Oscillating Magnetized Neutron Stars
We study the magnetosphere of a slowly rotating magnetized neutron star
subject to toroidal oscillations in the relativistic regime. Under the
assumption of a zero inclination angle between the magnetic moment and the
angular momentum of the star, we analyze the Goldreich-Julian charge density
and derive a second-order differential equation for the electrostatic
potential. The analytical solution of this equation in the polar cap region of
the magnetosphere shows the modification induced by stellar toroidal
oscillations on the accelerating electric field and on the charge density. We
also find that, after decomposing the oscillation velocity in terms of
spherical harmonics, the first few modes with are responsible for
energy losses that are almost linearly dependent on the amplitude of the
oscillation and that, for the mode , can be a factor
larger than the rotational energy losses, even for a velocity oscillation
amplitude at the star surface as small as . The results
obtained in this paper clarify the extent to which stellar oscillations are
reflected in the time variation of the physical properties at the surface of
the rotating neutron star, mainly by showing the existence of a relation
between and the oscillation amplitude. Finally, we propose a
qualitative model for the explanation of the phenomenology of intermittent
pulsars in terms of stellar oscillations that are periodically excited by star
glitches.Comment: 13 pages, 4 figures, submitted to MNRA
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