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2013
Impact Factor

Claudio Vidal

Av. Prof. Luiz Freire, s/n, Cidade Universitaria, Recife-Pe, Brasil
Departamento de Matematica, Universidade Federal de Pernambuco

Publications:

 Schmidt D. S., Vidal C. Stability of the Planar Equilibrium Solutions of a Restricted $1+N$ Body Problem 2014, vol. 19, no. 5, pp.  533-547 Abstract We started our studies with a planar Eulerian restricted four-body problem (ERFBP) where three masses move in circular orbits such that their configuration is always collinear. The fourth mass is small and does not influence the motion of the three primaries. In our model we assume that one of the primaries has mass 1 and is located at the origin and two masses of size $\mu$ rotate around it uniformly. The problem was studied in [3], where it was shown that there exist noncollinear equilibria, which are Lyapunov stable for small values of $\mu$. KAM theory is used to establish the stability of the equilibria. Our computations do not agree with those given in [3], although our conclusions are similar. The ERFBP is a special case of the $1+N$ restricted body problem with $N=2$. We are able to do the computations for any $N$ and find that the stability results are very similar to those for $N=2$. Since the $1+N$ body configuration can be stable when $N>6$, these results could be of more significance than for the case $N=2$. Keywords: $1+N$ body problem, relative equilibria, normal form, KAM stability Citation: Schmidt D. S., Vidal C.,  Stability of the Planar Equilibrium Solutions of a Restricted $1+N$ Body Problem , Regular and Chaotic Dynamics, 2014, vol. 19, no. 5, pp. 533-547 DOI:10.1134/S1560354714050025
 Dos Santos F., Vidal C. Stability of Equilibrium Solutions of Hamiltonian Systems Under the Presence of a Single Resonance in the Non-Diagonalizable Case 2008, vol. 13, no. 3, pp.  166-177 Abstract The problem of knowing the stability of one equilibrium solution of an analytic autonomous Hamiltonian system in a neighborhood of the equilibrium point in the case where all eigenvalues are pure imaginary and the matrix of the linearized system is non-diagonalizable is considered.We give information about the stability of the equilibrium solution of Hamiltonian systems with two degrees of freedom in the critical case. We make a partial generalization of the results to Hamiltonian systems with $n$ degrees of freedom, in particular, this generalization includes those in [1]. Keywords: Hamiltonian system, stability, normal form, resonances Citation: Dos Santos F., Vidal C.,  Stability of Equilibrium Solutions of Hamiltonian Systems Under the Presence of a Single Resonance in the Non-Diagonalizable Case, Regular and Chaotic Dynamics, 2008, vol. 13, no. 3, pp. 166-177 DOI:10.1134/S1560354708030039
 Santos A., Vidal C. Symmetry of the Restricted 4+1 Body Problem with Equal Masses 2007, vol. 12, no. 1, pp.  27-38 Abstract We consider the problem of symmetry of the central configurations in the restricted 4+1 body problem when the four positive masses are equal and disposed in symmetric configurations, namely, on a line, at the vertices of a square, at the vertices of a equilateral triangle with a mass at the barycenter, and finally, at the vertices of a regular tetrahedron [1-3]. In these situations, we show that in order to form a non collinear central configuration of the restricted 4+1 body problem, the null mass must be on an axis of symmetry. In our approach, we will use as the main tool the quadratic forms introduced by A. Albouy and A. Chenciner [4]. Our arguments are general enough, so that we can consider the generalized Newtonian potential and even the logarithmic case. To get our results, we identify some properties of the Newtonian potential (in fact, of the function $\varphi (s)=-s^k$, with $k<0$) which are crucial in the proof of the symmetry. Keywords: $n$-body problem, central configurations, symmetry Citation: Santos A., Vidal C.,  Symmetry of the Restricted 4+1 Body Problem with Equal Masses , Regular and Chaotic Dynamics, 2007, vol. 12, no. 1, pp. 27-38 DOI:10.1134/S1560354707010030
 Vidal C., Dos Santos F. Stability of equilibrium positions of periodic Hamiltonian systems under third and fourth order resonances 2005, vol. 10, no. 1, pp.  95-111 Abstract The problem of the stability of an equilibrium position of a nonautonomous 2$\pi$-periodic Hamiltonian system with $n$ degrees of freedom ($n \geqslant 2$), in a nonlinear setting, is studied in the presence of a single third and fourth order resonance. We give conditions of instability in the sense of Lyapunov and formal stability of the equilibrium position, depending on the coefficients of the Hamiltonian function. Keywords: periodic Hamiltonian system, Lyapunov stability, formal stability, resonance, normal form Citation: Vidal C., Dos Santos F.,  Stability of equilibrium positions of periodic Hamiltonian systems under third and fourth order resonances , Regular and Chaotic Dynamics, 2005, vol. 10, no. 1, pp. 95-111 DOI: 10.1070/RD2005v010n01ABEH000303