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

IAUC 4257 available at Central Bureau for Astronomical Telegrams. IAUC 4257 available at Central Bureau for Astronomical Telegrams.

When I was assigned the time in La Palma on the JKT, I gave thanks for my extraordinary luck that the observations were scheduled exactly at the perihelion of Comet LINEAR, or C/1999 S4 (LINEAR) as it is correctly known. This would be able to get data on the comet at the start of each night without interrupting the main programme. At the time I

We present Gran Telescopio CANARIAS CanariCam 8.7 μm imaging and 7.5-13 μm spectroscopy of six local systems known to host an active galactic nucleus (AGN) and have nuclear star formation. Our main goal is to investigate whether the molecules responsible for the 11.3 μm polycyclic aromatic hydrocarbon (PAH) feature are destroyed in the close