The notion that gravitation might lead to a breakdown of standard space-time structure at small distances, and that this might affect the propagation of ordinary particles has led to a program to search for violations of Lorentz invariance as a probe of quantum gravity. Initially it was expected that observable macroscopic effects caused by

We present a study of the ion{H}{i} distribution and dynamics of the nearby spiral galaxy NGC 5055 based on observations with the Westerbork Synthesis Radio Telescope. The gaseous disk of NGC 5055 extends out to about 40 kpc, equal to 3.5 R25, and shows a pronounced warp that starts at the end of the bright optical disk (R25= 11.6 kpc). This very

Local correlation tracking techniques are used to measure proper motions in a series of high angular resolution (~0.1") penumbra images. If these motions trace true plasma motions, then we have detected converging flows that arrange the plasma in long narrow filaments cospatial with dark penumbral filaments. Assuming that these flows are stationary

The stars β Cet, 31 Com, and μ Vel represent the main stages through which late-type giants evolve during their lifetime (the Hertzsprung gap [31 Com], the rapid braking zone [μ Vel], and the core helium burning ``clump'' phase [β Cet]). An analysis of their high-resolution Chandra X-ray spectra reveals similar coronal characteristics in terms of

To identify the mid-IR sources with optical objects we use the data from the Wide Field Survey (WFS, McMahon et al., 2001NewAR..45...97M). This survey has been carried out using the Wide Field Camera (WFC) on the 2.5-m Isaac Newton Telescope (INT) on the Observatorio del Roque de Los Muchachos (La Palma). (2 data files).

We report the discovery of a new M9.0 dwarf at only 8.2 pc, which we identified in our search for nearby ultracool dwarf (I-J>= 3.0, later than M8.0) in the DENIS data base. We measure a very high proper motion of 2.5arcsecyr-1. The PC3 index measured from its low-resolution spectrum gives a spectrophotometric distance of 8.2 pc. This makes it the