Results for "Á. Sódor"
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LCfit, a harmonic-function fitting programJun 01 2012In this note I announce and introduce the program LCfit developed for fitting harmonic functions to a data set, particularly to time-series data. LCfit stands for Linear Combination fitting. The diversity of light curve variations of Blazhko starsJan 26 2011The ground-based Konkoly Blazhko Survey I and II aim to collect accurate, extended, multicolour light curves of galactic field RRab stars in order to determine the incidence rate of the modulation in the sample, to study the modulation in details, to ... More KIC 2831097 - A 2-year orbital-period RR Lyrae binary candidateSep 21 2016We report the discovery of a new Kepler first-overtone RR Lyrae pulsator, KIC 2831097. The pulsation shows large, 0.1 d amplitude, systematic phase variations that can be interpreted as light travel-time effect caused by orbital motion in a binary system, ... More Amplitude Modulation in the ZZ Ceti Star GD 244Jun 23 2015Previous studies of GD 244 revealed seven pulsation frequencies (two doublets and three single periods) in the light variations of the star. The data obtained at McDonald Observatory between 2003 and 2006, and our additional measurements in 2006 and 2007 ... More Fitting Blazhko light curvesJun 08 2012The correct amplitude and phase modulation formalism of the Blazhko modulation is given. The harmonic order dependent amplitude and phase modulation form is equivalent with the Fourier decomposition of multiplets. The amplitude and phase modulation formalism ... More Affordable spectroscopy for 1m-class telescopesJan 15 2014Doppler observations of exoplanet systems have been a very expensive technique, mainly due to the high costs of high-resolution stable spectrographs. Recent advances in instrumentation enable affordable Doppler planet detections with surprisingly small ... More The Blazhko modulation of TV Boo in 2010Nov 15 2012We present the analysis of the multicolour CCD observations in the 2010 season of the Blazhko RRc star TV Boo. TV Boo shows a complex Blazhko modulation dominated by two independent modulations with P_{fm1}=9.74 d and P_{fm2}=21.43 d long periods. Both ... More The shortest modulation period Blazhko RR Lyrae star: SS CncMar 20 2006Extended BV(RI)c CCD observations of SS Cnc, a short period RRab star are presented. Nearly 1400 data points in each band have been obtained spanning over 79 days during the spring of 2005. The star exhibits light curve modulation, the so called Blazhko ... More The Multi-periodic Blazhko Modulation of CZ LacertaeSep 28 2010Thorough analysis of the multicolour CCD observations of the RRab-type variable, CZ Lacertae is presented. The observations were carried out in two consecutive observing seasons in 2004 and 2005 within the framework of the Konkoly Blazhko Survey of bright, ... More The triple-mode pulsating variable V823 CasAug 30 2005Based on extended multicolour CCD photometry of the triple-mode radial pulsator V823 Cas we studied the properties of the coupling frequencies invoked by nonlinear processes. Our results support that a resonance connection as suggested by Antonello & ... More Long-term photometric monitoring of RR Lyr stars in M3Sep 21 2011The period-change behaviour of 134 RR Lyrae stars in the globular cluster Messier 3 (M3) is investigated on the ~120-year time base of the photometric observations. The mean period-change rates (\beta \approx 0.01 d Myr^-1) of the subsamples of variables ... More Eötvös branesJun 25 2008Apr 21 2009The high value of brane tension has a crucial role in recovering Einstein's general relativity at low energies. In the framework of a recently developed formalism with variable brane tension one can pose the question, whether it was always that high? ... More Degenerate Hessian structures on radiant manifoldsMar 02 2015Oct 17 2016A manifold $M$ is said to be radiant if it is endowed with a distinguished atlas whose coordinate changes are locally linear transformations. Such manifolds are thereby furnished with a flat connection $\bar\nabla$ and a radiant vector field $\rho$ whose ... More A review of mean-shift algorithms for clusteringMar 02 2015A natural way to characterize the cluster structure of a dataset is by finding regions containing a high density of data. This can be done in a nonparametric way with a kernel density estimate, whose modes and hence clusters can be found using mean-shift ... More Variable tension brane-worldsFeb 26 2010I present recent work on codimension one brane-world models containing a 3+1 dimensional curved brane with time-dependent brane tension. Black holes on cosmological branesMar 08 2007While in general relativity black holes can be freely embedded into a cosmological background, the same problem in brane-worlds is much more cumbersome. We present here the results obtained so far in the explicit constructions of such space-times. We ... More On Hamiltonian formulations of the Schrödinger systemJan 09 2003We review and compare different variational formulations for the Schr\"{o}dinger field. Some of them rely on the addition of a conveniently chosen total time derivative to the hermitic Lagrangian. Alternatively, the Dirac-Bergmann algorithm yields the ... More Brane-world cosmology with black stringsMar 30 2006Jun 16 2006We consider the simplest scenario when black strings / cigars penetrate the cosmological brane. As a result, the brane has a Swiss-cheese structure, with Schwarzschild black holes immersed in a Friedmann-Lema\^{\i}tre-Robertson-Walker brane. There is ... More Debris Disks in Nearby Young Moving Groups in the ALMA EraOct 13 2015Many members of nearby young moving groups exhibit infrared excess attributed to circumstellar debris dust, formed via erosion of planetesimals. With their proximity and well-dated ages, these groups are excellent laboratories for studying the early evolution ... More Chromatic Derivatives and Expansions with WeightsJan 22 2016Chromatic derivatives and series expansions of bandlimited functions have recently been introduced in signal processing and they have been shown to be useful in practical applications. We extend the notion of chromatic derivative using varying weights. ... More Is dark matter futile on the brane?Dec 27 2006We investigate whether dark matter can be replaced by various source terms appearing in the effective Einstein equation, valid on a brane embedded into a higher dimensional space-time (the bulk). Such non-conventional source terms include a quadratic ... More Generalized Friedmann branesAug 21 2003Sep 19 2008We prove that for a large class of generalized Randall-Sundrum II type models the characterization of brane-gravity sector by the effective Einstein equation, Codazzi equation and the twice-contracted Gauss equation is equivalent with the bulk Einstein ... More No Swiss-cheese universe on the braneJul 02 2004Feb 22 2007We study the possibility of brane-world generalization of the Einstein-Straus Swiss-cheese cosmological model. We find the modifications induced by the brane-world scenario. At a first glance only the motion of the boundary is modified and the fluid in ... More Linear Einstein equations and Kerr-Schild mapsMar 28 2002We prove that given a solution of the Einstein equations $g_{ab}$ for the matter field $T_{ab}$, an autoparallel null vector field $l^{a}$ and a solution $(l_{a}l_{c}, \mathcal{T}_{ac})$ of the linearized Einstein equation on the given background, the ... More Spherically symmetric static solution for colliding null dustSep 04 1998The Einstein equations are integrated in the presence of two (incoming and outgoing) streams of null dust, under the assumptions of spherical symmetry and staticity. The solution is also written in double null and radiation coordinates and it is reinterpreted ... More The HATNet and HATSouth Exoplanet SurveysJan 02 2018The Hungarian-made Automated Telescope Network (HATNet) has been in operation since 2003, with the key science goal being the discovery and accurate characterization of transiting extrasolar planets (TEPs) around bright stars. Using six small, 11\,cm\ ... More Formulas on hyperbolic volumeOct 26 2010Nov 16 2010This paper collects some important formulas on hyperbolic volume. To determine concrete values of volume function is a very hard question requiring the knowledge of various methods. Our goal to give a non-elementary integral on the volume of the orthosceme ... More Dark energy from gravitational collapse?Jun 16 2006We discuss the status of both cosmological and black hole type singularities in the framework of the brane-world model of gravity. We point out that the Big Bang is not properly understood yet. We also show new features of the gravitational collapse on ... More Potential Theory and Quadratic ProgrammingNov 09 2016We extend the notion of some energy-type expressions based on two sets, developed in the abstract potential theory. We also give the discretized version of the quantities defined, similar to Chebyshev constant. This extension allows to apply the potential-theoretic ... More Weighted Fejér Constants and Fekete SetsJan 28 2013We give the connections among the Fekete sets, the zeros of orthogonal polynomials, $1(w)$-normal point systems, and the nodes of a stable and most economical interpolatory process via the Fej\'er contants. Finally the convergence of a weighted Gr\"unwald ... More Spin-spin effects in radiating compact binariesNov 22 1999The dynamics of a binary system with two spinning components on an eccentric orbit is studied, with the inclusion of the spin-spin interaction terms appearing at the second post-Newtonian order. A generalized true anomaly parametrization properly describes ... More Friedmann branes with variable tensionJun 24 2008Sep 22 2008We introduce brane-worlds with non-constant tension, strenghtening the analogy with fluid membranes, which exhibit a temperature-dependence according to the empirical law established by E\"otv\"os. This new degree of freedom allows for evolving gravitational ... More A homogeneous brane-world universeSep 11 2003A homogeneous, Kantowski-Sachs type, bouncing brane-world universe is presented. The bulk has a positive cosmological constant and the Killing algebra $so(1,3)\oplus so(3)$. The totality of the source terms of the effective Einstein equation combine to ... More Wormholes, naked singularities and universes of ghost radiationApr 03 2002Jan 09 2003Both the static and homogeneous metrics describing the spherically symmetric gravitational field of a crossflow of incoming and outgoing null dust streams are generalized for the case of the two-component ghost radiation. Static solutions represent either ... More Degenerate Hessian structures on radiant manifoldsMar 02 2015Sep 29 2017We present a rigorous mathematical treatment of Ruppeiner geometry, by considering degenerate Hessian metrics defined on radiant manifolds. A manifold $M$ is said to be radiant if it is endowed with a symmetric, flat connection $\bar\nabla$ and a global ... More Symmetric hyperbolic systems for Bianchi equationsMay 12 1998We obtain a family of first-order symmetric hyperbolic systems for the Bianchi equations. They have only physical characteristics: the light cone and timelike hypersurfaces. In the proof of the hyperbolicity, new positivity properties of the Bel tensor ... More Kerr-Schild metrics revisited I. The ground stateMar 26 2002The Kerr-Schild pencil of metrics $g_{ab}+\La l_al_b$ is investigated in the generic case when it maps an arbitrary vacuum space-time with metric $g_{ab}$ to a vacuum space-time. The theorem is proved that this generic case, with the field $l$ shearing, ... More New variables for brane-world gravityMar 23 2006Geometric variables naturally occurring in a time-like foliation of brane-worlds are introduced. These consist of the induced metric and two sets of lapse functions and shift vectors, supplemented by two sets of tensorial, vectorial and scalar variables ... More Hamiltonian theory of brane-world gravityDec 08 2006A brane-world universe consists of a 4-dimensional brane embedded into a 5-dimensional space-time (bulk). We apply the Arnowitt-Deser-Misner decomposition to the brane-world, which results in a 3+1+1 break-up of the bulk. We present the canonical theory ... More No solvable lambda-value term left behindApr 28 2016Jul 13 2016In the lambda calculus a term is solvable iff it is operationally relevant. Solvable terms are a superset of the terms that convert to a final result called normal form. Unsolvable terms are operationally irrelevant and can be equated without loss of ... More Linear Viscoelastic Shells: An Asymptotic ApproachApr 08 2016We consider a family of linear viscoelastic shells with thickness $2\varepsilon$ ( $\varepsilon$ , small parameter), clamped along a portion of their lateral face, all having the same middle surface $S$. We formulate the three-dimensional mechanical problem ... More Testing General Relativity With Laser Accelerated Electron BeamsJul 16 2012Electron accelerations of the order of $10^{21} g$ obtained by laser fields open up the possibility of experimentally testing one of the cornerstones of general relativity, the weak equivalence principle, which states that the local effects of a gravitational ... More Covariant gravitational dynamics in 3+1+1 dimensionsSep 02 2009May 11 2010We develop a 3+1+1 covariant formalism with cosmological and astrophysical applications. First we give the evolution and constraint equations both on the brane and off-brane in terms of 3-space covariant kinematical, gravito-electro-magnetic (Weyl) and ... More Asymmetric Swiss-cheese brane-worldsAug 27 2006Jul 31 2007We study a brane-world cosmological scenario with local inhomogeneities represented by black holes. The brane is asymmetrically embedded into the bulk. The black strings/cigars penetrating the Friedmann brane generate a Swiss-cheese type structure. This ... More Kerr-Schild metrics revisited II. The complete vacuum solutionMar 26 2002The complete solution of Einstein's gravitational equations with a vacuum-vacuum Kerr-Schild pencil of metrics $g_{ab}+V l_al_b$ is obtained. Our result generalizes the solution of the Kerr-Schild problem with a flat metric $g_{ab}$ (represented by the ... More Weak gravitational lensing in brane-worldsFeb 20 2006We derive the deflection angle of light rays caused by a brane black hole with mass m and tidal charge q in the weak lensing approach, up to the second order in perturbation theory. We point out when the newly derived second order contributions become ... More Solution of the vacuum Kerr-Schild problemMar 26 2002The complete solution of the vacuum Kerr-Schild equations in general relativity is presented, including the space-times with a curved background metric. The corresponding result for a flat background has been obtained by Kerr. Irradiated asymmetric Friedmann branesJan 29 2006We consider a Friedmann brane moving in a bulk impregnated by radiation. The setup is strongly asymmetric, with only one black hole in the bulk. The radiation emitted by this bulk black hole can be reflected, absorbed or transmitted through the brane. ... More Gravitational dynamics in s+1+1 dimensionsJul 06 2005Mar 06 2006We present the concomitant decomposition of an (s+2)-dimensional spacetime both with respect to a timelike and a spacelike direction. The formalism we develop is suited for the study of the initial value problem and for canonical gravitational dynamics ... More