La Plata International School (LAPIS)http://sedici.unlp.edu.ar:80/handle/10915/1676142024-09-07T11:57:22Z2024-09-07T11:57:22ZWavelets Analysis for Time SeriesChristen, Alejandrahttp://sedici.unlp.edu.ar:80/handle/10915/1677672024-07-04T20:02:25Z2021-01-01T00:00:00ZObjeto de conferencia
VIII La Plata International School: Pulsations Along Stellar Evolution (La Plata, 11 al 22 de noviembre de 2019); Pulsations Along Stellar Evolution: Proceedings of the VIII La Plata International School
Wavelet analysis has been widely used to analyze time series and has countless applications in astronomy. Because of its characteristics it is a method that is well suited to approximate functions, eliminate noise, detect points of change, discontinuities and periodicities. In this article an introduction to the wavelet theory and its use in time series is presented. Numerical simulations and some real examples are developed in the software R.
2021-01-01T00:00:00ZWavelet analysis has been widely used to analyze time series and has countless applications in astronomy. Because of its characteristics it is a method that is well suited to approximate functions, eliminate noise, detect points of change, discontinuities and periodicities. In this article an introduction to the wavelet theory and its use in time series is presented. Numerical simulations and some real examples are developed in the software R.Theoretical Description and Basic Physics of Stellar PulsationsGlatzel, Wolfganghttp://sedici.unlp.edu.ar:80/handle/10915/1677662024-07-04T20:02:29Z2021-01-01T00:00:00ZObjeto de conferencia
VIII La Plata International School: Pulsations Along Stellar Evolution (La Plata, 11 al 22 de noviembre de 2019); Pulsations Along Stellar Evolution: Proceedings of the VIII La Plata International School
As an introduction to the subject basic properties of stellar pulsations are derived using simple intuitive estimates. With respect to a theoretical description of pulsating stars the physical principles governing stellar structure and dynamics are discussed. The associated equations are simplified by the assumption of spherical symmetry thus providing the basis for the study of radial pulsations.
2021-01-01T00:00:00ZAs an introduction to the subject basic properties of stellar pulsations are derived using simple intuitive estimates. With respect to a theoretical description of pulsating stars the physical principles governing stellar structure and dynamics are discussed. The associated equations are simplified by the assumption of spherical symmetry thus providing the basis for the study of radial pulsations.Pulsations in Evolved Massive StarsKraus, Michaelahttp://sedici.unlp.edu.ar:80/handle/10915/1677652024-07-04T20:02:33Z2021-01-01T00:00:00ZObjeto de conferencia
VIII La Plata International School: Pulsations Along Stellar Evolution (La Plata, 11 al 22 de noviembre de 2019); Pulsations Along Stellar Evolution: Proceedings of the VIII La Plata International School
The post-main sequence evolution of massive stars still bears many unknowns. In particular, the physical processes involved in triggering enhanced mass-loss or eruptions are yet to be established. In this Chapter, the post-main sequence evolution of massive stars, and the various phases which are well-known for their mass ejections, are briefly touched upon. Amongst those transition phases, two classes of objects are discussed in more detail: the B-type supergiants and the Yellow Hypergiants. Their ability to perform pulsations is presented based on observational and theoretical evidences. Moreover, the possibility of a pulsation-mass-loss relation in these two classes of objects is delineated.
2021-01-01T00:00:00ZThe post-main sequence evolution of massive stars still bears many unknowns. In particular, the physical processes involved in triggering enhanced mass-loss or eruptions are yet to be established. In this Chapter, the post-main sequence evolution of massive stars, and the various phases which are well-known for their mass ejections, are briefly touched upon. Amongst those transition phases, two classes of objects are discussed in more detail: the B-type supergiants and the Yellow Hypergiants. Their ability to perform pulsations is presented based on observational and theoretical evidences. Moreover, the possibility of a pulsation-mass-loss relation in these two classes of objects is delineated.Pulsating Hot Subdwarf StarsRomero, Alejandra Danielahttp://sedici.unlp.edu.ar:80/handle/10915/1677642024-07-04T20:02:40Z2021-01-01T00:00:00ZObjeto de conferencia
VIII La Plata International School: Pulsations Along Stellar Evolution (La Plata, 11 al 22 de noviembre de 2019); Pulsations Along Stellar Evolution: Proceedings of the VIII La Plata International School
Hot subdwarf stars are core helium-burning objects, located at the hot end of the horizontal branch, and therefore, they are also known as Extreme Horizontal Branch stars. We can divide them into two large groups, of spectral types B and O, depending on their effective temperature. Each spectroscopic class has subgroups showing luminosity variations due to pulsations, opening the possibility to study these compact objects through Asteroseismology. In this notes I will briefly review the main characteristics of hot subdwarfs B and O stars and the different pulsating subgroups.
2021-01-01T00:00:00ZHot subdwarf stars are core helium-burning objects, located at the hot end of the horizontal branch, and therefore, they are also known as Extreme Horizontal Branch stars. We can divide them into two large groups, of spectral types B and O, depending on their effective temperature. Each spectroscopic class has subgroups showing luminosity variations due to pulsations, opening the possibility to study these compact objects through Asteroseismology. In this notes I will briefly review the main characteristics of hot subdwarfs B and O stars and the different pulsating subgroups.Pulsating A-F StarsSánchez Arias, Julieta Pazhttp://sedici.unlp.edu.ar:80/handle/10915/1677622024-07-04T20:02:44Z2021-01-01T00:00:00ZObjeto de conferencia
VIII La Plata International School: Pulsations Along Stellar Evolution (La Plata, 11 al 22 de noviembre de 2019); Pulsations Along Stellar Evolution: Proceedings of the VIII La Plata International School
This Chapter provides a brief description of the different classes of pulsating A-F stars emphasising hybrids δ Sct-γ Dor stars. A modelling technique for hybrid δ Sct-γ Dor stars is presented along with the typical features that these stars “print” on their light curves and frequency spectra. Finally, we present a very different family of pulsating stars overlapping the region where pulsating A-F stars usually lie, the precursors of the so-called extremely low mass white dwarf stars. These stars have very similar atmospheric characteristics and their oscillation periods partially overlap making them difficult to discern. We discuss tools based on their seismic oscillation properties to distinguish them.
2021-01-01T00:00:00ZThis Chapter provides a brief description of the different classes of pulsating A-F stars emphasising hybrids δ Sct-γ Dor stars. A modelling technique for hybrid δ Sct-γ Dor stars is presented along with the typical features that these stars “print” on their light curves and frequency spectra. Finally, we present a very different family of pulsating stars overlapping the region where pulsating A-F stars usually lie, the precursors of the so-called extremely low mass white dwarf stars. These stars have very similar atmospheric characteristics and their oscillation periods partially overlap making them difficult to discern. We discuss tools based on their seismic oscillation properties to distinguish them.Observing Techniques and MissionsKraus, Michaelahttp://sedici.unlp.edu.ar:80/handle/10915/1677222024-07-03T20:01:44Z2021-01-01T00:00:00ZObjeto de conferencia
VIII La Plata International School: Pulsations Along Stellar Evolution (La Plata, 11 al 22 de noviembre de 2019); Pulsations Along Stellar Evolution: Proceedings of the VIII La Plata International School
Stellar pulsations can cause variability in the brightness of the star as well as in the shape and radial velocity of photospheric lines. To determine the periods and modes of pulsations, two different but complementary observational techniques are in use: photometric light curves to measure the brightness variations, and spectroscopic time series to analyze the time-dependent motions at the stellar surface. In the first part of this Chapter, both observing techniques and their sources of errors and limitations are presented. In the second part, an overview of the various space and ground-based missions for both photometry and spectroscopy is given. Considering all the currently available and newly planned instruments, the future for research in variable and pulsating stars is bright.
2021-01-01T00:00:00ZStellar pulsations can cause variability in the brightness of the star as well as in the shape and radial velocity of photospheric lines. To determine the periods and modes of pulsations, two different but complementary observational techniques are in use: photometric light curves to measure the brightness variations, and spectroscopic time series to analyze the time-dependent motions at the stellar surface. In the first part of this Chapter, both observing techniques and their sources of errors and limitations are presented. In the second part, an overview of the various space and ground-based missions for both photometry and spectroscopy is given. Considering all the currently available and newly planned instruments, the future for research in variable and pulsating stars is bright.Numerical Treatment of Linear and Nonlinear Stellar PulsationsGlatzel, Wolfganghttp://sedici.unlp.edu.ar:80/handle/10915/1677212024-07-03T20:01:52Z2021-01-01T00:00:00ZObjeto de conferencia
VIII La Plata International School: Pulsations Along Stellar Evolution (La Plata, 11 al 22 de noviembre de 2019); Pulsations Along Stellar Evolution: Proceedings of the VIII La Plata International School
The linear stability analysis of stellar models poses a linear fourth or sixth order boundary eigenvalue problem. Methods for its numerical solution are reviewed, most of which face severe problems, if the ratio of the thermal and dynamical timescale falls below unity for a significant fraction of the stellar envelope considered. The extremely robust and highly accurate Riccati method is introduced and shown to be applicable to stellar stability problems with success even in these cases of strong deviations from adiabaticity. Numerical simulations of the evolution of a stellar instability into the nonlinear regime are still restricted to spherical geometry. We address the basic requirements for and problems connected with the simulation of radial pulsations. How violent artificial initial perturbations may be avoided and the extremely high accuracy requirements posed by the differences between the various energy forms can be met by strictly conservative numerical schemes is discussed.
2021-01-01T00:00:00ZThe linear stability analysis of stellar models poses a linear fourth or sixth order boundary eigenvalue problem. Methods for its numerical solution are reviewed, most of which face severe problems, if the ratio of the thermal and dynamical timescale falls below unity for a significant fraction of the stellar envelope considered. The extremely robust and highly accurate Riccati method is introduced and shown to be applicable to stellar stability problems with success even in these cases of strong deviations from adiabaticity. Numerical simulations of the evolution of a stellar instability into the nonlinear regime are still restricted to spherical geometry. We address the basic requirements for and problems connected with the simulation of radial pulsations. How violent artificial initial perturbations may be avoided and the extremely high accuracy requirements posed by the differences between the various energy forms can be met by strictly conservative numerical schemes is discussed.Low Amplitude Adiabatic Non-radial Stellar OscillationsBenvenuto, Omar Gustavohttp://sedici.unlp.edu.ar:80/handle/10915/1677202024-07-03T20:01:55Z2021-01-01T00:00:00ZObjeto de conferencia
VIII La Plata International School: Pulsations Along Stellar Evolution (La Plata, 11 al 22 de noviembre de 2019); Pulsations Along Stellar Evolution: Proceedings of the VIII La Plata International School
We present the problem of low amplitude, adiabatic non-radial oscillations starting from first principles. We describe the perturbations imposed to the models, assuming that its non-perturbed structure is spherical. Then, we restrict ourselves to the case of adiabatic oscillations, presenting the equations written in terms of the Dziem- bowski variables. We describe a numerical method for solving these equations based on finite differences and apply it for the simple case of polytropic spheres. A computer code based on this algorithm is available at the web page of the school. This method can be easily generalised for computing the case of low amplitude, non-adiabatic, non-radial pulsations.
2021-01-01T00:00:00ZWe present the problem of low amplitude, adiabatic non-radial oscillations starting from first principles. We describe the perturbations imposed to the models, assuming that its non-perturbed structure is spherical. Then, we restrict ourselves to the case of adiabatic oscillations, presenting the equations written in terms of the Dziem- bowski variables. We describe a numerical method for solving these equations based on finite differences and apply it for the simple case of polytropic spheres. A computer code based on this algorithm is available at the web page of the school. This method can be easily generalised for computing the case of low amplitude, non-adiabatic, non-radial pulsations.Linear AnalysisGlatzel, Wolfganghttp://sedici.unlp.edu.ar:80/handle/10915/1677192024-07-03T20:01:59Z2021-01-01T00:00:00ZObjeto de conferencia
VIII La Plata International School: Pulsations Along Stellar Evolution (La Plata, 11 al 22 de noviembre de 2019); Pulsations Along Stellar Evolution: Proceedings of the VIII La Plata International School
We discuss the general strategy of the theoretical description of stellar stability and pulsations. The initial construction of a spherically symmetric stellar model in hydrostatic equilibrium is followed by considering small perturbations around the equilibrium. Both for radial and nonradial disturbances the linear equations governing these small perturbations are derived. The influence of the thermal and the dynamical timescale on the properties of linear pulsations is discussed in detail. For unstable stellar models the last step of the general approach consists of following the evolution of an instability into the nonlinear regime by numerical simulation.
2021-01-01T00:00:00ZWe discuss the general strategy of the theoretical description of stellar stability and pulsations. The initial construction of a spherically symmetric stellar model in hydrostatic equilibrium is followed by considering small perturbations around the equilibrium. Both for radial and nonradial disturbances the linear equations governing these small perturbations are derived. The influence of the thermal and the dynamical timescale on the properties of linear pulsations is discussed in detail. For unstable stellar models the last step of the general approach consists of following the evolution of an instability into the nonlinear regime by numerical simulation.Analysis Techniques: the Lomb-Scargle PeriodogramCarpintero, Daniel Diegohttp://sedici.unlp.edu.ar:80/handle/10915/1677182024-07-03T20:02:03Z2021-01-01T00:00:00ZObjeto de conferencia
VIII La Plata International School: Pulsations Along Stellar Evolution (La Plata, 11 al 22 de noviembre de 2019); Pulsations Along Stellar Evolution: Proceedings of the VIII La Plata International School
Fourier’s traditional signal analysis does not work when observations are not equispaced in time, as is usually the case in Astronomy. The Lomb Scargle periodogram is the favorite substitute. We will study the basics of this technique and some care that needs to be taken for its practical application and its interpretation.
2021-01-01T00:00:00ZFourier’s traditional signal analysis does not work when observations are not equispaced in time, as is usually the case in Astronomy. The Lomb Scargle periodogram is the favorite substitute. We will study the basics of this technique and some care that needs to be taken for its practical application and its interpretation.A Brief Introduction to Stellar EvolutionBenvenuto, Omar Gustavohttp://sedici.unlp.edu.ar:80/handle/10915/1677172024-07-03T20:02:09Z2021-01-01T00:00:00ZObjeto de conferencia
VIII La Plata International School: Pulsations Along Stellar Evolution (La Plata, 11 al 22 de noviembre de 2019); Pulsations Along Stellar Evolution: Proceedings of the VIII La Plata International School
With the aim of providing a reference frame for the study of stellar pulsations we describe the process known as stellar evolution. Evolution and pulsations are deeply related and the knowledge gained in one of them has an immediate impact on the other. First we describe the observational basis, presenting the Hertzsprung-Russell Diagram and other fundamental concepts. Then we describe the physical context of stellar evolution in which, quite fortunately, matter is very close to (but not in) thermodynamic equilibrium. This allows for a simplification of the problem of paramount importance. We describe the equation of state of stellar matter, paying attention on when we should expect the occurrence of partial and full ionization (fundamental for pulsations), and electron degeneracy. Then, we present the concept of hydrostatic equilibrium. As a natural consequence we consider barotropic structures, like polytropic spheres and cold white dwarfs, discussing the existence of the Chandrasekhar’s mass limit. As realistic stars are not cold but at finite temperature (they radiate energy in space!), in general they are nonbarotropic. So, we need to consider the conservation of energy and also its transport by radiation, convection and conduction. As it is well known, the engine of stars is nuclear reactions. We present the proton-proton and carbon-nitrogen-oxygen cycles of hydrogen burning and also the main helium burning reactions. Then, we make some brief comments on the methods for solving the full set of non-linear, partial differential equations of stellar evolution and also those needed for computing the changes of chemical composition. At this point we are in conditions to present stellar evolution as a direct consequence of these physical ingredients. We discuss the main stages of stellar evolution for a variety of objects: pre-main sequence, low and intermediate mass, white dwarfs, and finally massive stars. In this paper we restricted ourselves to the case of isolated and nonrotating objects evolving during their long lived stages. In our opinion, this provides a general basis for most of the usually considered pulsating stars.
2021-01-01T00:00:00ZWith the aim of providing a reference frame for the study of stellar pulsations we describe the process known as stellar evolution. Evolution and pulsations are deeply related and the knowledge gained in one of them has an immediate impact on the other. First we describe the observational basis, presenting the Hertzsprung-Russell Diagram and other fundamental concepts. Then we describe the physical context of stellar evolution in which, quite fortunately, matter is very close to (but not in) thermodynamic equilibrium. This allows for a simplification of the problem of paramount importance. We describe the equation of state of stellar matter, paying attention on when we should expect the occurrence of partial and full ionization (fundamental for pulsations), and electron degeneracy. Then, we present the concept of hydrostatic equilibrium. As a natural consequence we consider barotropic structures, like polytropic spheres and cold white dwarfs, discussing the existence of the Chandrasekhar’s mass limit. As realistic stars are not cold but at finite temperature (they radiate energy in space!), in general they are nonbarotropic. So, we need to consider the conservation of energy and also its transport by radiation, convection and conduction. As it is well known, the engine of stars is nuclear reactions. We present the proton-proton and carbon-nitrogen-oxygen cycles of hydrogen burning and also the main helium burning reactions. Then, we make some brief comments on the methods for solving the full set of non-linear, partial differential equations of stellar evolution and also those needed for computing the changes of chemical composition. At this point we are in conditions to present stellar evolution as a direct consequence of these physical ingredients. We discuss the main stages of stellar evolution for a variety of objects: pre-main sequence, low and intermediate mass, white dwarfs, and finally massive stars. In this paper we restricted ourselves to the case of isolated and nonrotating objects evolving during their long lived stages. In our opinion, this provides a general basis for most of the usually considered pulsating stars.Pulsations Along Stellar Evolution: Proceedings of the VIII La Plata International
SchoolKraus, MichaelaTorres, Andrea F.http://sedici.unlp.edu.ar:80/handle/10915/1676602024-07-05T17:44:51Z2021-01-01T00:00:00ZLibro
Kraus, Michaela; Torres, Andrea F.
The VIII La Plata International School was successfully held in the period 2019 November 11 - 22 on the campus of the Universidad Nacional de La Plata. The school was organized by the research group Modelos de Estrellas Peculiares (MEP) of the Facultad de Ciencias Astronómicas y Geofísicas (FCAG).
The subject of this school was Pulsations Along Stellar Evolution. The offered lectures covered a wide range of topics such as stellar evolution, theoretical concepts of stellar pulsations, observing and data analysis techniques, along with practical courses for the analysis of selected pulsating stars. The ultimate goal of the Summer School was that the participants deepen their understanding of the physics of stellar pulsations and learn relevant techniques to analyze and properly interpret observational data of pulsating stars. This was achieved by the active participation in a number of courses dealing with theoretical exercises and practical computer-based exercises. This volume provides a comprehensive summary of the lectures that were presented during the school.
Asociación Argentina de Astronomía,
2021-01-01T00:00:00ZThe VIII La Plata International School was successfully held in the period 2019 November 11 - 22 on the campus of the Universidad Nacional de La Plata. The school was organized by the research group Modelos de Estrellas Peculiares (MEP) of the Facultad de Ciencias Astronómicas y Geofísicas (FCAG).
The subject of this school was Pulsations Along Stellar Evolution. The offered lectures covered a wide range of topics such as stellar evolution, theoretical concepts of stellar pulsations, observing and data analysis techniques, along with practical courses for the analysis of selected pulsating stars. The ultimate goal of the Summer School was that the participants deepen their understanding of the physics of stellar pulsations and learn relevant techniques to analyze and properly interpret observational data of pulsating stars. This was achieved by the active participation in a number of courses dealing with theoretical exercises and practical computer-based exercises. This volume provides a comprehensive summary of the lectures that were presented during the school.The periodic and chaotic regimes of motion in the exoplanet 2/1 mean-motion resonanceMichtchenko, Tatiana AlexandrovnaFerraz-Mello, SylvioBeaugé, Cristianhttp://sedici.unlp.edu.ar:80/handle/10915/1676572024-07-01T20:01:59Z2012-01-01T00:00:00ZObjeto de conferencia
III La Plata International School on Astronomy and Geophysics (La Plata,11 al 15 de julio de 2011); 3rd La Plata International School on Astronomy and Geophysics
We present the dynamical structure of the phase space of the planar planetary 2/1 mean-motion resonance (MMR). Inside the resonant domain, there exist two families of periodic orbits, one associated to the librational motion of the critical angle (c-family) and the other related to the circulatory motion of the angle between the pericentres (Aw-family). The well-known apsidal corotation resonances (ACR) appear at the intersections of these families. A complex web of secondary resonances exists also for low eccentricities, whose strengths and positions are dependent on the individual masses and spatial scale of the system.
Depending on initial conditions, a resonant system is found in one of the two topologically different states, referred to as internal and external resonances. The internal resonance is characterized by symmetric ACR and its resonant angle is 2 λ₂ — λ₁— ͞ω₁, where λᵢ and Wi stand for the planetary mean longitudes and longitudes of pericentre, respectively. In contrast, the external resonance is characterized by asymmetric ACR and the resonant angle is 2 λ₂ — λ₁ — ͞ω₂. We show that systems with more massive outer planets always envolve inside internal resonances. The limit case is the well-known asteroidal resonances with Jupiter. At variance, systems with more massive inner planets may evolve in either internal or external resonances; the internal resonances are typical for low-to- moderate eccentricity configurations, whereas the external ones for high eccentricity configurations of the systems. In the limit case, analogous to Kuiper belt objects in resonances with Neptune, the systems are always in the external resonances characterized by asymmetric equilibria.
2012-01-01T00:00:00ZWe present the dynamical structure of the phase space of the planar planetary 2/1 mean-motion resonance (MMR). Inside the resonant domain, there exist two families of periodic orbits, one associated to the librational motion of the critical angle (c-family) and the other related to the circulatory motion of the angle between the pericentres (Aw-family). The well-known apsidal corotation resonances (ACR) appear at the intersections of these families. A complex web of secondary resonances exists also for low eccentricities, whose strengths and positions are dependent on the individual masses and spatial scale of the system.
Depending on initial conditions, a resonant system is found in one of the two topologically different states, referred to as internal and external resonances. The internal resonance is characterized by symmetric ACR and its resonant angle is 2 λ₂ — λ₁— ͞ω₁, where λᵢ and Wi stand for the planetary mean longitudes and longitudes of pericentre, respectively. In contrast, the external resonance is characterized by asymmetric ACR and the resonant angle is 2 λ₂ — λ₁ — ͞ω₂. We show that systems with more massive outer planets always envolve inside internal resonances. The limit case is the well-known asteroidal resonances with Jupiter. At variance, systems with more massive inner planets may evolve in either internal or external resonances; the internal resonances are typical for low-to- moderate eccentricity configurations, whereas the external ones for high eccentricity configurations of the systems. In the limit case, analogous to Kuiper belt objects in resonances with Neptune, the systems are always in the external resonances characterized by asymmetric equilibria.Simple Instability in a 3D Autonomous Hamiltonian system of galactic typeKatsanikas, Matthaioshttp://sedici.unlp.edu.ar:80/handle/10915/1676562024-07-01T20:02:03Z2012-01-01T00:00:00ZObjeto de conferencia
III La Plata International School on Astronomy and Geophysics (La Plata,11 al 15 de julio de 2011); 3rd La Plata International School on Astronomy and Geophysics
In this paper we study the orbital behavior in the neighborhood of simple unstable periodic orbits in a 3D rotating galactic potential. We use the method of color and rotation to visualize the 4D spaces of section. We found four types of structures in the 4D space of section that correspond to four types of orbits. The first three types are sticky chaotic orbits and in the last one the orbit visits all available phase space.
2012-01-01T00:00:00ZIn this paper we study the orbital behavior in the neighborhood of simple unstable periodic orbits in a 3D rotating galactic potential. We use the method of color and rotation to visualize the 4D spaces of section. We found four types of structures in the 4D space of section that correspond to four types of orbits. The first three types are sticky chaotic orbits and in the last one the orbit visits all available phase space.Renormalization tools to study the loss of stability in the Area Preserving MapsOlvera, Arturohttp://sedici.unlp.edu.ar:80/handle/10915/1676552024-07-01T20:02:06Z2012-01-01T00:00:00ZObjeto de conferencia
III La Plata International School on Astronomy and Geophysics (La Plata,11 al 15 de julio de 2011); 3rd La Plata International School on Astronomy and Geophysics
The renormalization method for area preserving maps was introduced by R. S. MacKay in 1982 to study critical invariant circles. Similar ideas appear in the study of critical phenomena in physics (MacKay 1983). The renormalization scenario for the breakdown of golden invarian circles in the twist map is described in this paper. In the first part we describe the renormalization methods introduced by MacKay. In the second part, the obstruction criterion (Olvera & Simó 1987) is described and we show that the renormalization group and the obstruction criterion can work together (De la Llave & Olvera 2006).
2012-01-01T00:00:00ZThe renormalization method for area preserving maps was introduced by R. S. MacKay in 1982 to study critical invariant circles. Similar ideas appear in the study of critical phenomena in physics (MacKay 1983). The renormalization scenario for the breakdown of golden invarian circles in the twist map is described in this paper. In the first part we describe the renormalization methods introduced by MacKay. In the second part, the obstruction criterion (Olvera & Simó 1987) is described and we show that the renormalization group and the obstruction criterion can work together (De la Llave & Olvera 2006).Methods of algebraic manipulation in perturbation theoryGiorgilli, AntonioSansottera, Marcohttp://sedici.unlp.edu.ar:80/handle/10915/1676532024-07-01T20:02:10Z2012-01-01T00:00:00ZObjeto de conferencia
III La Plata International School on Astronomy and Geophysics (La Plata,11 al 15 de julio de 2011); 3rd La Plata International School on Astronomy and Geophysics
We give a short introduction to the methods of representing polynomial and trigonometric series that are often used in Celestial Mechanics. A few applications are also illustrated.
2012-01-01T00:00:00ZWe give a short introduction to the methods of representing polynomial and trigonometric series that are often used in Celestial Mechanics. A few applications are also illustrated.Faraway matter as a possible substitute for dark matterCarati, AndreaGalgani, Luigihttp://sedici.unlp.edu.ar:80/handle/10915/1676512024-07-01T20:02:17Z2012-01-01T00:00:00ZObjeto de conferencia
III La Plata International School on Astronomy and Geophysics (La Plata,11 al 15 de julio de 2011); 3rd La Plata International School on Astronomy and Geophysics
A review is given of an attempt, made in two recent papers, to estimate the gravitational action of faraway matter on a test particle, in connection with the velocity dispersion in clusters of galaxies and with the rotation curves of spiral galaxies, respectively. Under the assumptions that faraway matter has a fractal distribution and that the gravitational action has a correlation length of the order of some kiloparsec, the gravitational action of faraway matter appears to be sufficient to explain the observations relative to such two phenomena, without invoking any local, dark matter contribution.
2012-01-01T00:00:00ZA review is given of an attempt, made in two recent papers, to estimate the gravitational action of faraway matter on a test particle, in connection with the velocity dispersion in clusters of galaxies and with the rotation curves of spiral galaxies, respectively. Under the assumptions that faraway matter has a fractal distribution and that the gravitational action has a correlation length of the order of some kiloparsec, the gravitational action of faraway matter appears to be sufficient to explain the observations relative to such two phenomena, without invoking any local, dark matter contribution.Dynamical origin of V-type asteroids outside the Vesta familyRoig, FernandoFolonier, HugoBeaugé, CristiánRibeiro, Anderson O.http://sedici.unlp.edu.ar:80/handle/10915/1676482024-07-01T20:02:25Z2012-01-01T00:00:00ZObjeto de conferencia
III La Plata International School on Astronomy and Geophysics (La Plata,11 al 15 de julio de 2011); 3rd La Plata International School on Astronomy and Geophysics
We review some recent results on the long term dynamical evolution of V-type asteroids that point to their origin as fugitives from the Vesta family. Three scenarios are explored: (i) interplay of weak mean motion and non linear secular resonances in the inner Belt with the Yarkovsky effect, (ii) crossing of the 3:1 mean motion resonance with Jupiter, and (iii) evolution by planetary encounters and resonance stickiness. These mechanisms may explain a large fraction of the V-type asteroids that are observed outside the Vesta family, but there are some particular cases that would need other explanations.
2012-01-01T00:00:00ZWe review some recent results on the long term dynamical evolution of V-type asteroids that point to their origin as fugitives from the Vesta family. Three scenarios are explored: (i) interplay of weak mean motion and non linear secular resonances in the inner Belt with the Yarkovsky effect, (ii) crossing of the 3:1 mean motion resonance with Jupiter, and (iii) evolution by planetary encounters and resonance stickiness. These mechanisms may explain a large fraction of the V-type asteroids that are observed outside the Vesta family, but there are some particular cases that would need other explanations.Dynamical chaos in the Solar systemShevchenko, Ivan I.http://sedici.unlp.edu.ar:80/handle/10915/1676452024-07-01T20:02:30Z2012-01-01T00:00:00ZObjeto de conferencia
III La Plata International School on Astronomy and Geophysics (La Plata,11 al 15 de julio de 2011); 3rd La Plata International School on Astronomy and Geophysics
Methods and results of a new major part of science on the dynamics of the Solar system bodies, namely, the part devoted to researches of dynamical chaos in the motion of celestial bodies, are described and analyzed. The dynamical chaos (non-determined dynamical behavior in the absence of any random perturbations) in the motion of celestial bodies is caused by interaction of nonlinear resonances, either orbital or spin-orbit. The resonances and chaos in the motion of minor and large bodies of the Solar system, — planetary satellites, asteroids, comets, and planets, are considered. Special attention is given to the problem of observability of the chaotic behavior; in particular, methods of analytical estimating the Lyapunov time, specifying the “predictability horizon” of the motion, are described.
2012-01-01T00:00:00ZMethods and results of a new major part of science on the dynamics of the Solar system bodies, namely, the part devoted to researches of dynamical chaos in the motion of celestial bodies, are described and analyzed. The dynamical chaos (non-determined dynamical behavior in the absence of any random perturbations) in the motion of celestial bodies is caused by interaction of nonlinear resonances, either orbital or spin-orbit. The resonances and chaos in the motion of minor and large bodies of the Solar system, — planetary satellites, asteroids, comets, and planets, are considered. Special attention is given to the problem of observability of the chaotic behavior; in particular, methods of analytical estimating the Lyapunov time, specifying the “predictability horizon” of the motion, are described.Diffusion measurements in a 3DoF Hamiltonian flowMestre, Martín FedericoCincotta, Pablo MiguelGiordano, Claudia Marcelahttp://sedici.unlp.edu.ar:80/handle/10915/1676442024-07-01T20:02:34Z2012-01-01T00:00:00ZObjeto de conferencia
III La Plata International School on Astronomy and Geophysics (La Plata,11 al 15 de julio de 2011); 3rd La Plata International School on Astronomy and Geophysics
We present measurements of diffusion phenomenae in the phase space of a three degree of freedom guasz-integrable Hamiltonian flow. By tracking the evolution of the variance of ensembles of test particles, we characterize the diffusion as basically anomalous. We find a time range in which it can be considered as a subdiffusion process and other in which it can be considered as a normal diffusion process. In the former case we fit Hurst exponents and in the latter case we compute diffusion coefficients based on the rate of growth of the variances.
2012-01-01T00:00:00ZWe present measurements of diffusion phenomenae in the phase space of a three degree of freedom guasz-integrable Hamiltonian flow. By tracking the evolution of the variance of ensembles of test particles, we characterize the diffusion as basically anomalous. We find a time range in which it can be considered as a subdiffusion process and other in which it can be considered as a normal diffusion process. In the former case we fit Hurst exponents and in the latter case we compute diffusion coefficients based on the rate of growth of the variances.