TypeIa supernovae are thought to occur when a white dwarf made of carbon and oxygen accretes sufficient mass to trigger a thermonuclear explosion. The accretion could be slow, from an unevolved (main-sequence) or evolved (subgiant or giant) star (the single-degenerate channel), or rapid, as the primary star breaks up a smaller orbiting white dwarf

We analyse new integral-field spectroscopy of the inner region (central 2.5 kpc) of the spiral galaxy NGC 4321 to study the peculiar kinematics of this region. Fourier analysis of the velocity residuals obtained by subtracting an axisymmetric rotation model from the Hα velocity field indicates that the distortions are global features generated by

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