25,037 research outputs found
Microlensing path parametrization for Earth-like Exoplanet detection around solar mass stars
We propose a new parametrization of the impact parameter u0 and impact angle
{\alpha} for microlensing systems composed by an Earth-like Exoplanet around a
Solar mass Star at 1 AU. We present the caustic topology of such system, as
well as the related light curves generated by using such a new parametrization.
Based on the same density of points and accuracy of regular methods, we obtain
results 5 times faster for discovering Earth-like exoplanet. In this big data
revolution of photometric astronomy, our method will impact future missions
like WFIRST (NASA) and Euclid (ESA) and they data pipelines, providing a rapid
and deep detection of exoplanets for this specific class of microlensing event
that might otherwise be lost.Comment: 8 pages, 7 figures, accepted to be published in The Astronomical
Journa
Hilbert Space of Isomorphic Representations of Bosonized Chiral
We analyse the Hilbert space structure of the isomorphic gauge non-invariant
and gauge invariant bosonized formulations of chiral for the particular
case of the Jackiw-Rajaraman parameter . The BRST subsidiary conditions
are found not to provide a sufficient criterium for defining physical states in
the Hilbert space and additional superselection rules must to be taken into
account. We examine the effect of the use of a redundant field algebra in
deriving basic properties of the model. We also discuss the constraint
structure of the gauge invariant formulation and show that the only primary
constraints are of first class.Comment: LaTeX, 19 page
Magnetovac Cylinder to Magnetovac Torus
A method for mapping known cylindrical magnetovac solutions to solutions in
torus coordinates is developed. Identification of the cylinder ends changes
topology from R1 x S1 to S1 x S1. An analytic Einstein-Maxwell solution for a
toroidal magnetic field in tori is presented. The toroidal interior is matched
to an asymptotically flat vacuum exterior, connected by an Israel boundary
layer.Comment: to appear in Class. Quant. Gra
Minimal resonances in annular non-Euclidean strips
Differential growth processes play a prominent role in shaping leaves and
biological tissues. Using both analytical and numerical calculations, we
consider the shapes of closed, elastic strips which have been subjected to an
inhomogeneous pattern of swelling. The stretching and bending energies of a
closed strip are frustrated by compatibility constraints between the curvatures
and metric of the strip. To analyze this frustration, we study the class of
"conical" closed strips with a prescribed metric tensor on their center line.
The resulting strip shapes can be classified according to their number of
wrinkles and the prescribed pattern of swelling. We use this class of strips as
a variational ansatz to obtain the minimal energy shapes of closed strips and
find excellent agreement with the results of a numerical bead-spring model.
Within this class of strips, we derive a condition under which a strip can have
vanishing mean curvature along the center line.Comment: 14 pages, 13 figures. Published version. Updated references and added
2 figure
On the differential geometry of curves in Minkowski space
We discuss some aspects of the differential geometry of curves in Minkowski
space. We establish the Serret-Frenet equations in Minkowski space and use them
to give a very simple proof of the fundamental theorem of curves in Minkowski
space. We also state and prove two other theorems which represent Minkowskian
versions of a very known theorem of the differential geometry of curves in
tridimensional Euclidean space. We discuss the general solution for torsionless
paths in Minkowki space. We then apply the four-dimensional Serret-Frenet
equations to describe the motion of a charged test particle in a constant and
uniform electromagnetic field and show how the curvature and the torsions of
the four-dimensional path of the particle contain information on the
electromagnetic field acting on the particle.Comment: 10 pages. Typeset using REVTE
The solar, exoplanet and cosmological lithium problems
We review three Li problems. First, the Li problem in the Sun, for which some
previous studies have argued that it may be Li-poor compared to other Suns.
Second, we discuss the Li problem in planet hosting stars, which are claimed to
be Li-poor when compared to field stars. Third, we discuss the cosmological Li
problem, i.e. the discrepancy between the Li abundance in metal-poor stars
(Spite plateau stars) and the predictions from standard Big Bang
Nucleosynthesis. In all three cases we find that the "problems" are naturally
explained by non-standard mixing in stars.Comment: Astrophysics and Space Science, in press. New version has one
reference correcte
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