Non-Ideal Plasma of the Sun
Physical and Chemical Evolution of Nonideal Plasma of the Sun Inferred from Modern Helioseismic Data
Tech Area / Field
- PHY-PLS/Plasma Physics/Physics
- PHY-NGD/Fluid Mechanics and Gas Dynamics/Physics
- INF-DAT/Data Storage and Peripherals/Information and Communications
- INF-SOF/Software/Information and Communications
- SAT-AST/Astronomy/Space, Aircraft and Surface Transportation
8 Project completed
Senior Project Manager
Malakhov Yu I
VNIITF, Russia, Chelyabinsk reg., Snezhinsk
- TRINITI, Russia, Moscow reg., Troitsk\nMoscow State University / Sternberg State Institute of Astronomy, Russia, Moscow
- University of Aarthus / Department of Physics and Astronomy, Denmark, Aarhus\nUniversity of Southern California / College of Letters, Arts and Sciences, USA, CA, Los-Angeles\nUniversität Rostock / Institut für Physik, Germany, Rostock\nPolitecnico di Torino, Italy, Torino
Project summaryIn modern astrophysics the model of the Sun is understood as a simulation of how the distribution of solar plasma chemical composition evolves in time starting from the initial homogeneous stage until the modern state of the Sun. A detailed description of the evolution of the Sun is necessary for realistic forecasting of processes on the Earth and in the solar system. That is because the structure and evolution of the Sun determine the chemical composition of the planets, as well as their formation conditions and further evolution. The change of macroscopic parameters of the Sun during the evolution (brightness and radius growth, the surface temperature change, a possibility of non-steady evolution stages) determines the whole fortune of the solar system bodies
The standard model of solar composition was formed by the mid 20th century and was widely recognized up to the late 80s, and was based on some substantially simplified assumptions. It was supposed as sufficient to consider only the basic components, such as hydrogen and helium, these could be converted by means of the thermonuclear reactions localized in the solar core. It was assumed that all intermediate components of the transformation chain are in equilibrium, i. e. reactions were considered as single-stage ones.
At the same time, last years the extensive data on highly accurate helioseismological observation of eigenfrequencies of solar vibrations were received and gave the information on profiles of sound speed and density inside the Sun. Thus, these data provide possibility to receive the information on physical conditions in deep layers and, as a result, specify essentially standard model: now the accuracy of theoretically calculated frequencies by one - two orders exceeds the level of accuracy of the observation.
The purpose of this project is to develop an improved model of the Sun based on the latest achievements in describing the properties of weakly non-ideal plasma and the processes which take place in the Sun by making use of the most recent results from helioseismology.
The model is intended to be developed in the following directions: adjustment of the EOS to describe the states of components in the medium, introduction of more accurate values of opacity factors for the medium and fusion reaction rates, usage of the turbulent intermixing models to describe convective energy transport, consideration of diffusion processes and segregation of heavy components, as they essentially influence the chemical elements distribution along the solar radius.
The research institutes engaged in this project have developed the application codes for modeling the complex gas-dynamic processes including diffusion and media segregation, thermodynamic properties and opacity factors of multicomponent plasma. Except for that, physical models have been developed for kinetic processes and composition variations due to thermonuclear burning in the solar plasma environment. Russian participants are recognized as highly experienced teams in the appropriate areas of research.
The adaptation of the existing radiating hydrodynamics program complex to solar plasma conditions will be the goal of the project. It will allow to simulate processes in solar plasma and estimate the influence of the made approximations on model of the Sun. As a result of verification of physical models on the basis of helioseismic data analysis will be constructed the model of chemical evolution of the Sun.
Improvement of the description of the physical phenomena and processes in the solar plasma will be based on the published helioseismological data on profiles of sound speed and density of species on radius inside the Sun. To make more precise the EOS of weakly non-ideal solar plasma the multicomponent composition of solar plasma and its radial dependence will be taken into account. This EOS will be compared with earlier published equations. For correct description of radiation transport processes it is supposed to use the refined opacity data that reflect the radial change of chemical and ionic composition of plasma. Improvement of these data will be carried out by the detailed description of structure for spectra of the whole amount of bounded-bounded and bounded-free transitions, and also by a due account for plasma effects. For the description of convective transfer areas the semi-empirical k-ε model of turbulent mixture will be used. The parameters of the model will be adjusted using the experimental data and the results of direct numerical simulation. In contrast to former models suitable to calculate the width of convective transport zone, this model will allow determining the boundaries of convective zone in a self-consistent way. Processes of diffusion and separation of heavy elements in a gravitational field are important to describe the radial distribution of chemical elements and, hence, to improve the EOS and media opacity data. These processes will also be taken into account. Also more precise expressions for fusion reactions rates caused by influence of fast particles will be derived.
The obtained data will be used to describe the current state and evolution of the Sun. On the basis of the received results the analysis of influence of each physical parameter on final model and on radial profiles of physical characteristics inside the Sun will be carried out.
Realization of the project will gave possibility not only to improve the standard model of the Sun significantly, but also to develop the up-to-date theoretical concepts of non-ideal plasma physics as a whole. As a result, computer models for the description of physical parameters of plasma with a multiparameter chemical composition will be created. These models can be applied not only in astrophysics, but also in other applied and basic research, and in engineering calculations of plasma chemical and power installations. The project results are intended for public and noncommercial use in fundamental and applied scientific research, and also for university educational programs. They will be published in leading physical and astronomical journals, and also in Internet on a special Web-site of the project.