Verlinde gravity effects on the orbits of the planets and the Moon in the Solar System

In this work, we address the effects of a phenomenon known as Verlinde gravity. Here we show that its effect over the planets and the Moon in our Solar System is quite negligible. We find that the Verlinde gravity effects on the orbits of planets are at least 10 times smaller than the precision with which we can determine the Sun’s mass, and the one on the orbit of the Moon is about 100 times smaller than the precision with which we can determine the Earth’s mass. These results let us infer that statements in the literature that Verlinde gravity is ruled out by the observed motion of planets in our Solar System are not correct.Fil: Yoon, Youngsub. Investigador Independiente; Corea del SurFil: Darriba, Luciano Ariel. Consejo Nacional de Investigaciones Científicas y Técnicas. Centro Científico Tecnológico Conicet - La Plata. Instituto de Astrofísica La Plata. Universidad Nacional de La Plata. Facultad de Ciencias Astronómicas y Geofísicas. Instituto de Astrofísica La Plata; Argentin

Estudio empírico de la difusión caótica en sistemas conservativos

Cuando queremos estudiar la dinámica de un sistema, por ejemplo una galaxia o un sistema planetario, es importante primero conocer en qué regiones del sistema una órbita tiene un comportamiento regular y en cuáles un comportamiento caótico. Las herramientas que utilizaremos para abordar esta cuestión son los llamados indicadores de caos. Existen en la literatura una gran cantidad de estos indicadores, de los cuales en este trabajo utilizaremos aquéllos basados en la evolución de la solución de las ecuaciones variacionales. Algunos ejemplos de este tipo de indicadores son el Máximo Exponente de Lyapunov (lLCE), el Indicador Rápido de Lyapunov (FLI) y su variante que considera solo la componente ortogonal (OFLI), el Factor de Crecimiento Exponencial Medio de Órbitas Cercanas (MEGNO), el Índice Menor de Alineamiento (SALI), entre otros. En el Capítulo 2 revisaremos las principales características de una variedad de este tipo de indicadores. Luego, en el Capítulo 3 presentaremos un código, escrito en FORTRAN, que integra de una forma eficiente todos los indicadores descriptos en el Capítulo 2. Hemos desarrollado dos versiones de este programa, una para mapas simplécticos y otra para flujos hamiltonianos. La primera será empleada en la segunda parte de este trabajo, y ambas versiones fueron utilizadas en la tesis doctoral del Dr. Nicolás Maffione. La segunda parte de este trabajo está dedicada al estudio, dentro de la región caótica, de la difusión, esto es, determinar si existe una variación secular de las integrales no perturbadas del sistema. Para valores perturbativos muy pequeños se encontraron escenarios en los que la difusión no era detectable a causa de las oscilaciones introducidas por los efectos de deformación del conjunto de variables utilizadas, por lo que recurrimos al uso de las formas normales. Dado que no existía hasta el momento una implementación de esta técnica para el caso de mapas, en este trabajo se creó, por primera vez en la literatura, dicha implementación. Esta herramienta es una sucesión de transformaciones canónicas que permite describir, de una forma más clara, la dinámica del sistema, eliminando justamente los efectos de deformación. En el Capítulo 4 presentaremos, de una manera detallada, el mecanismo para la construcción de las formas normales para un mapa simpléctico 4D cuasi-torsional general. En el Capítulo 5 mostraremos cómo aplicar dicho mecanismo a dos mapas estándar acoplados. Dado que las formas normales se construyen mediante series de Fourier, presentaremos los resultados de la medición de los tiempos de CPU empleados para distintos órdenes de este desarrollo. También presentaremos una estimación empírica del orden óptimo para el cual construir la forma normal, para dos escenarios distintos. Finalmente, en el Capítulo 6 llevaremos a cabo el estudio de la difusión, que es el objetivo central de este trabajo. Este estudio lo realizaremos a través de la medición de la desviación cuadrática media de la acción en la dirección de la resonancia con respecto a su valor inicial. Estudiaremos un ensamble de 103 partículas considerando varios escenarios distintos mediante la variación del parámetro de acoplamiento del mapa.Facultad de Ciencias Astronómicas y Geofísica

LP-VIcode: a program to compute a suite of variational chaos indicators

An important point in analyzing the dynamics of a given stellar or planetary system is the reliable identification of the chaotic or regular behavior of its orbits. We introduce here the program LP-VIcode, a fully operational code which efficiently computes a suite of ten variational chaos indicators for dynamical systems in any number of dimensions. The user may choose to simultaneously compute any number of chaos indicators among the following: the Lyapunov Exponents, the Mean Exponential Growth factor of Nearby Orbits, the Slope Estimation of the largest Lyapunov Characteristic Exponent, the Smaller ALignment Index, the Generalized ALignment Index, the Fast Lyapunov Indicator, the Orthogonal Fast Lyapunov Indicator, the dynamical Spectra of Stretching Numbers, the Spectral Distance, and the Relative Lyapunov Indicator. They are combined in an efficient way, allowing the sharing of differential equations whenever this is possible, and the individual stopping of their computation when any of them saturates.Instituto de Astrofísica de La PlataFacultad de Ciencias Astronómicas y Geofísica

LP-VIcode: a program to compute a suite of variational chaos indicators

An important point in analyzing the dynamics of a given stellar or planetary system is the reliable identification of the chaotic or regular behavior of its orbits. We introduce here the program LP-VIcode, a fully operational code which efficiently computes a suite of ten variational chaos indicators for dynamical systems in any number of dimensions. The user may choose to simultaneously compute any number of chaos indicators among the following: the Lyapunov Exponents, the Mean Exponential Growth factor of Nearby Orbits, the Slope Estimation of the largest Lyapunov Characteristic Exponent, the Smaller ALignment Index, the Generalized ALignment Index, the Fast Lyapunov Indicator, the Orthogonal Fast Lyapunov Indicator, the dynamical Spectra of Stretching Numbers, the Spectral Distance, and the Relative Lyapunov Indicator. They are combined in an efficient way, allowing the sharing of differential equations whenever this is possible, and the individual stopping of their computation when any of them saturates.Instituto de Astrofísica de La PlataFacultad de Ciencias Astronómicas y Geofísica

Water worlds in N-body simulations with fragmentation in systems without gaseous giants

We analyze the formation and evolution of terrestrial-like planets around solar-type stars in the absence of gaseous giants. In particular, we focus on the physical and dynamical properties of those that survive in the system´s Habitable Zone (HZ). This investigation is based on a comparative study between N-body simulations that include fragmentation and others that consider all collisions as perfect mergers.We use an N-body code, presented in a previous paper, that allows planetary fragmentation. We carry out three sets of 24 simulations for 400 Myr. Two sets are developed adopting a model that includes hit-and-run collisions and planetary fragmentation, each one with different values of the individual minimum mass allowed for the fragments. For the third set, we considered that all collisions lead to perfect mergers.The planetary systems produced in N-body simulations with and without fragmentation are broadly similar, with some differences. In simulations with fragmentation, the formed planets have lower masses since part it is distributed amongst collisional fragments. Additionally, those planets presented lower eccentricities, presumably due to dynamical friction with the generated fragments. Lastly, perfect mergers and hit-and-run collisions are the most common outcome.Regardless of the collisional treatment adopted, most of the planets that survive in the HZ start the simulation beyond the snow line, having very high final water contents. Such planets are called water worlds. The fragments´ contribution to their final mass and water content is negligible. Finally, the individual minimum mass for fragments may play an important role in the planets´ collisional history.Collisional models that incorporate fragmentation and hit-and-run collisions lead to a more detailed description of the physical properties of the terrestrial-like planets formed. We conclude that planetary fragmentation is not a barrier to the formation of water worlds in the HZ. The results shown in this work suggest that further refinement is necessary to have a more realistic model of planetary formation.Fil: Dugaro, Agustin. Consejo Nacional de Investigaciones Científicas y Técnicas. Centro Científico Tecnológico Conicet - La Plata. Instituto de Astrofísica La Plata. Universidad Nacional de La Plata. Facultad de Ciencias Astronómicas y Geofísicas. Instituto de Astrofísica La Plata; ArgentinaFil: de Elia, Gonzalo Carlos. Consejo Nacional de Investigaciones Científicas y Técnicas. Centro Científico Tecnológico Conicet - La Plata. Instituto de Astrofísica La Plata. Universidad Nacional de La Plata. Facultad de Ciencias Astronómicas y Geofísicas. Instituto de Astrofísica La Plata; ArgentinaFil: Darriba, Luciano Ariel. Consejo Nacional de Investigaciones Científicas y Técnicas. Centro Científico Tecnológico Conicet - La Plata. Instituto de Astrofísica La Plata. Universidad Nacional de La Plata. Facultad de Ciencias Astronómicas y Geofísicas. Instituto de Astrofísica La Plata; Argentin

Role of gaseous giants in the dynamical evolution of terrestrial planets and water delivery in the habitable zone

In this research, we study the effects of a single giant planet on the dynamical evolution of water-rich embryos and planetesimals, located beyond the snow line of systems around Sun-like stars, in order to determine what kind of terrestrial-like planets could be formed in the habitable zone (HZ) of these systems. To do this, we carry out N-body simulations of planetary accretion, considering that the gas has been already dissipated from the disc and a single giant planet has been formed beyond the snow line of the system, at 3 au. We find that a giant planet with a value of mass between Saturn mass and Jupiter mass represents a limit from which the amount of water-rich embryos that move inward from beyond the snow line starts to decrease. From this, our research suggests that giant planets more massive than one Jupiter mass become efficient dynamical barriers to inward-migrating water-rich embryos. Moreover, we infer that the number of these embryos that survive in the HZ decreases significantly for systems that host a giant planet more massive than one Jupiter mass. This result has important consequences concerning the formation of terrestrial-like planets in the HZ with very high water content and could provide a selection criterion in the search for potentially habitable exoplanets in systems that host a gaseous giant around solar-type stars.Instituto de Astrofísica de La Plat

Role of gaseous giants in the dynamical evolution of terrestrial planets and water delivery in the habitable zone

In this research, we study the effects of a single giant planet on the dynamical evolution of water-rich embryos and planetesimals, located beyond the snow line of systems around Sun-like stars, in order to determine what kind of terrestrial-like planets could be formed in the habitable zone (HZ) of these systems. To do this, we carry out N-body simulations of planetary accretion, considering that the gas has been already dissipated from the disc and a single giant planet has been formed beyond the snow line of the system, at 3 au. We find that a giant planet with a value of mass between Saturn mass and Jupiter mass represents a limit from which the amount of water-rich embryos that move inward from beyond the snow line starts to decrease. From this, our research suggests that giant planets more massive than one Jupiter mass become efficient dynamical barriers to inward-migrating water-rich embryos. Moreover, we infer that the number of these embryos that survive in the HZ decreases significantly for systems that host a giant planet more massive than one Jupiter mass. This result has important consequences concerning the formation of terrestrial-like planets in the HZ with very high water content and could provide a selection criterion in the search for potentially habitable exoplanets in systems that host a gaseous giant around solar-type stars.Instituto de Astrofísica de La Plat

Chaos detection tools: application to a self-consistent triaxial model

Together with the variational indicators of chaos, the spectral analysis methods have also achieved great popularity in the field of chaos detection. The former are based on the concept of local exponential divergence. The latter are based on the numerical analysis of some particular quantities of a single orbit, e.g. its frequency. In spite of having totally different conceptual bases, they are used for the very same goals such as, for instance, separating the chaotic and the regular component. In fact, we show herein that the variational indicators serve to distinguish both components of a Hamiltonian system in a more reliable fashion than a spectral analysis method does. We study two start spaces for different energy levels of a self?consistent triaxial stellar dynamical model by means of some selected variational indicators and a spectral analysis method. In order to select the appropriate tools for this paper, we extend previous studies where we make a comparison of several variational indicators on different scenarios. Herein, we compare the Average Power Law Exponent (APLE) and an alternative quantity given by the Mean Exponential Growth factor of Neary Orbits (MEGNO): the MEGNO?s Slope Estimation of the largest Lyapunov Characteristic Exponent (SElLCE). The spectral analysis method selected for the investigation is the Frequency Modified Fourier Transform (FMFT). Besides a comparative study of the APLE, the Fast Lyapunov Indicator (FLI), the Orthogonal Fast Lyapunov Indicator (OFLI) and the MEGNO/SElLCE, we show that the SElLCE could be an appropriate alternative to the MEGNO when studying large samples of initial conditions. The SElLCE separates the chaotic and the regular components reliably and identifies the different levels of chaoticity. We show that the FMFT is not as reliable as the SElLCE to describe clearly the chaotic domains in the experiments. We use the latter indicator as the main variational indicator to analyse the phase space portraits of the model under study.Fil: Maffione, Nicolas Pablo. Consejo Nacional de Investigaciones Científicas y Técnicas. Centro Científico Tecnológico La Plata. Instituto de Astrofísica de La Plata; Argentina. Universidad Nacional de la Plata. Facultad de Ciencias Astronómicas y Geofísicas; ArgentinaFil: Darriba, Luciano Ariel. Consejo Nacional de Investigaciones Científicas y Técnicas. Centro Científico Tecnológico La Plata. Instituto de Astrofísica de La Plata; Argentina. Universidad Nacional de la Plata. Facultad de Ciencias Astronómicas y Geofísicas; ArgentinaFil: Cincotta, Pablo Miguel. Consejo Nacional de Investigaciones Científicas y Técnicas. Centro Científico Tecnológico La Plata. Instituto de Astrofísica de La Plata; Argentina. Universidad Nacional de la Plata. Facultad de Ciencias Astronómicas y Geofísicas; ArgentinaFil: Giordano, Claudia Marcela. Consejo Nacional de Investigaciones Científicas y Técnicas. Centro Científico Tecnológico La Plata. Instituto de Astrofísica de La Plata; Argentina. Universidad Nacional de la Plata. Facultad de Ciencias Astronómicas y Geofísicas; Argentin

Comparative study of variational chaos indicators and ODEs' numerical integrators

The reader can find in the literature a lot of different techniques to study the dynamics of a given system and also, many suitable numerical integrators to compute them. Notwithstanding the recent work of Maffione et al. (2011a) for mappings, a detailed comparison among the widespread indicators of chaos in a general system is still lacking. Such a comparison could lead to select the most efficient algorithms given a certain dynamical problem. Furthermore, in order to choose the appropriate numerical integrators to compute them, more comparative studies among numerical integrators are also needed. This work deals with both problems. We first extend the work of Maffione et al. (2011) for mappings to the 2D H\'enon & Heiles (1964) potential, and compare several variational indicators of chaos: the Lyapunov Indicator (LI); the Mean Exponential Growth Factor of Nearby Orbits (MEGNO); the Smaller Alignment Index (SALI) and its generalized version, the Generalized Alignment Index (GALI); the Fast Lyapunov Indicator (FLI) and its variant, the Orthogonal Fast Lyapunov Indicator (OFLI); the Spectral Distance (D) and the Dynamical Spectras of Stretching Numbers (SSNs). We also include in the record the Relative Lyapunov Indicator (RLI), which is not a variational indicator as the others. Then, we test a numerical technique to integrate Ordinary Differential Equations (ODEs) based on the Taylor method implemented by Jorba & Zou (2005) (called taylor), and we compare its performance with other two well-known efficient integrators: the Prince & Dormand (1981) implementation of a Runge-Kutta of order 7-8 (DOPRI8) and a Bulirsch-St\"oer implementation. These tests are run under two very different systems from the complexity of their equations point of view: a triaxial galactic potential model and a perturbed 3D quartic oscillator.Instituto de Astrofísica de La Plat

Chaos detection tools: application to a self-consistent triaxial model

Together with the variational indicators of chaos, the spectral analysis methods have also achieved great popularity in the field of chaos detection. The former are based on the concept of local exponential divergence. The latter are based on the numerical analysis of some particular quantities of a single orbit, e.g. its frequency. In spite of having totally different conceptual bases, they are used for the very same goals such as, for instance, separating the chaotic and the regular components. In fact, we show herein that the variational indicators serve to distinguish both components of a Hamiltonian system in a more reliable fashion than a spectral analysis method does. We study two start spaces for different energy levels of a self-consistent triaxial stellar dynamical model by means of some selected variational indicators and a spectral analysis method. In order to select the appropriate tools for this paper, we extend previous studies where we make a comparison of several variational indicators on different scenarios. Herein, we compare the average power-law exponent (APLE) and an alternative quantity given by the mean exponential growth factor of nearby orbits (MEGNO): the MEGNO's slope estimation of the largest Lyapunov characteristic exponent (SElLCE). The spectral analysis method selected for the investigation is the frequency modified Fourier transform (FMFT). Besides a comparative study of the APLE, the fast Lyapunov indicator (FLI), the orthogonal fast Lyapunov indicator (OFLI) and theMEGNO/SElLCE, we show that the SElLCE could be an appropriate alternative to the MEGNO when studying large samples of initial conditions. The SElLCE separates the chaotic and the regular components reliably and identifies the different levels of chaoticity. We show that the FMFT is not as reliable as the SElLCE to describe clearly the chaotic domains in the experiments. We use the latter indicator as the main variational indicator to analyse the phase space portraits of the model under study.Facultad de Ciencias Astronómicas y GeofísicasInstituto de Astrofísica de La Plat