In this paper we present a high resolution IR spectrum of the planetary nebula Hb5, over the range 1.6-1.75 micron. Our aim is to test the hypothesis invoking emission from upper vibrational levels in excited PAH molecules and anharmonicity of the C-H stretching mode to explain the weak features observed in the 3 micron range. The predicted first

Non-LTE calculations of H-alpha line profiles are presented and applied to derive rotational velocities from high-resolution spectra of DA white dwarfs. This paper extends recent work by Pilachowski and Milkey (1984, 1987) to southern hemisphere objects and confirms their findings that all white dwarfs seem to be slow rotators. Of the seven objects

Current astronomical measurements indicate that approximately 73% of the universe is made up of dark energy. Stochastically quantized self-interacting scalar fields can serve as suitable models to generate dark energy. We study a particular model where the scalar field theory underlying dark energy exhibits strongest possible chaotic behaviour. It

The mathematical structure of nonlinear, isentropic longitudinal flows of an ideal magnetohydrodynamic plasma confined to a magnetic flux tube embedded in a quiescent nonmagnetic fluid is investigated. Exact analytical solutions are derived for a special type of nonlinear flow in the absence of gravity: the simple waves, for which all the unknowns

We present results of nonlinear, two-dimensional, numerical simulations of magneto-acoustic wave propagation in the photosphere and chromosphere of small-scale flux tubes with internal structure. Waves with realistic periods of three to five minutes are studied, after horizontal and vertical oscillatory perturbations are applied to the equilibrium

The nonlinear development of the kink instability in a horizontal magnetic flux tube with a field strength exceeding the equipartition value lying initially in the deep convective zone is calculated. A Lagrangian numerical code is developed to obtain solutions for the system of equations dictating the evolution of a thin magnetic flux tube in a