2,424 research outputs found
Image Subtraction Reduction of Open Clusters M35 & NGC 2158 In The K2 Campaign-0 Super-Stamp
Observations were made of the open clusters M35 and NGC 2158 during the
initial K2 campaign (C0). Reducing these data to high-precision photometric
time-series is challenging due to the wide point spread function (PSF) and the
blending of stellar light in such dense regions. We developed an
image-subtraction-based K2 reduction pipeline that is applicable to both
crowded and sparse stellar fields. We applied our pipeline to the data-rich C0
K2 super-stamp, containing the two open clusters, as well as to the neighboring
postage stamps. In this paper, we present our image subtraction reduction
pipeline and demonstrate that this technique achieves ultra-high photometric
precision for sources in the C0 super-stamp. We extract the raw light curves of
3960 stars taken from the UCAC4 and EPIC catalogs and de-trend them for
systematic effects. We compare our photometric results with the prior
reductions published in the literature. For detrended, TFA-corrected sources in
the 12--12.25 magnitude range, we achieve a best 6.5 hour window
running rms of 35 ppm falling to 100 ppm for fainter stars in the 14--14.25 magnitude range. For stars with , our detrended and
6.5 hour binned light curves achieve the highest photometric precision.
Moreover, all our TFA-corrected sources have higher precision on all time
scales investigated. This work represents the first published image subtraction
analysis of a K2 super-stamp. This method will be particularly useful for
analyzing the Galactic bulge observations carried out during K2 campaign 9. The
raw light curves and the final results of our detrending processes are publicly
available at \url{http://k2.hatsurveys.org/archive/}.Comment: Accepted for publication in PASP. 14 pages, 5 figures, 2 tables.
Light curves available from http://k2.hatsurveys.org/archive
The self-energy of a charged particle in the presence of a topological defect distribution
In this work we study a charged particle in the presence of both a continuous
distribution of disclinations and a continuous distribution of edge
dislocations in the framework of the geometrical theory of defects. We obtain
the self-energy for a single charge both in the internal and external regions
of either distribution. For both distributions the result outside the defect
distribution is the self-energy that a single charge experiments in the
presence of a single defect.Comment: 12 pages, Revtex4, two figures,to appear in Int. Joun. Mod. Phys.
Enhancing the handling of standard substitution weights on a hydrostatic weighing apparatus
project “17RPT02-rhoLiqThe hydrostatic weighing apparatus is a first-level method used to measure the density of solids and liquids. At the Portuguese Institute for Quality the hydrostatic tests for the determination of the liquids’ density implies the multiple manual placement of a set of standard substitution weights on apparatus’ balance pan, leading to undesirable perturbations in the weighing environment. Also, by this the eccentricity effects on the balance, contribute for an unwanted increase of the measurement uncertainty. To overcome these phenomena, an automated mechanism was designed and implemented, which allows the placing and recollection of the set of standard weights on the balance. To validate the new mechanism, tests to ultrapure water at 20 °C were executed before and after its implementation and the obtained results were compared. Despite a 3-fold increase in density measurement uncertainty, mainly due to the exposure of the standard substitution weights to air convection currents, the execution of hydrostatic tests was improved, not only for the fact that the measurements are now carried out quicker, but also for the fact that the operator only needs to intervene once during the whole test. Moreover, the smaller absolute deviation from the reference density value for ultrapure water at 20 °C results also in a normalised error En lower than 1 (0.3), thus validating the designed automated mechanism for the handling of standard substitution weights.publishersversionpublishe
Horizon Fractalization in Black Strings Ungravity
In this paper we study the scalar(tensor) and vector unparticle corrections
for cosmic and black strings. Initially we have considered an static cosmic
string ansatz from which we obtain the solution in terms of first and second
kind Bessel functions. We have also obtained the solution for black string in
the unparticle scenario. We could identify two regimes, namely, a gravity
dominated regime and an ungravity dominated regime. In the gravity dominated
regime the black string solution recovers the usual solution for black strings.
The Hawking temperature was also studied in both regimes and in the ungravity
dominated regime. As in the static and rotating black hole, we found a
fractalization of the event horizon. This points to the fact that
fractalization is a natural consequence of unparticles. Finally, we study the
thermodynamic of the black string in the ungravity scenario by computing the
entropy, heat capacity and free energy. For both cases we find that, depending
on the region of the parameter , we can have phase transitions.Comment: 18 pages, 6 figure
Falsifying Tree Level String Motivated Bouncing Cosmologies
The string effective action at tree level contains, in its bosonic sector,
the Einstein-Hilbert term, the dilaton, and the axion, besides scalar and gauge
fields coming from the Ramond-Ramond sector. The reduction to four dimensions
brings to scene moduli fields. We generalize this effective action by
introducing two arbitrary parameters, and , connected with the
dilaton and axion couplings. In this way, more general frameworks can be
analyzed. Regular solutions with a bounce can be obtained for a range of
(negative) values of the parameter which, however, exclude the pure
string configuration (). We study the evolution of scalar
perturbations in such cosmological scenarios. The predicted primordial power
spectrum decreases with the wavenumber with spectral index , in
contradiction with the results of the . Hence, all such effective string
motivated cosmological bouncing models seem to be ruled out, at least at the
tree level approximation.Comment: Latex file, 19 pages, 3 figures in eps forma
Brane Structure from a Scalar Field in Warped Spacetime
We deal with scalar field coupled to gravity in five dimensions in warped
geometry. We investigate models described by potentials that drive the system
to support thick brane solutions that engender internal structure. We find
analytical expressions for the brane solutions, and we show that they are all
linearly stable.Comment: 10 pages, 7 eps figures; version to be published in JCA
ARTICULAR SONOGRAPHY in HEALTHY INDIVIDUALS: COMPARISON AMONG SMALL, MEDIUM and LARGE JOINTS
Universidade Federal de São Paulo, São Paulo, BrazilUniversidade Federal de São Paulo, São Paulo, BrazilWeb of Scienc
Spacetime Defects: von K\'arm\'an vortex street like configurations
A special arrangement of spinning strings with dislocations similar to a von
K\'arm\'an vortex street is studied. We numerically solve the geodesic
equations for the special case of a test particle moving along twoinfinite rows
of pure dislocations and also discuss the case of pure spinning defects.Comment: 9 pages, 2figures, CQG in pres
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