Aims:Motivated by recent observations of oscillations in coronal arcades, we investigate analytically the influence of longitudinal structuring on the modes of oscillation of a straight coronal loop arcade. As a first step towards more complicated models, we use a simple structure to obtain analytical solutions. Methods: A partial differential

In this paper we discuss the observational consequences of a dependence of meteor brightness on the entry angle z_R_, namely the decrease of the observed rates of meteors and the reduction of the population indices r for radiant zenith distances larger than zero. These effects, if not properly accounted for, lead to erroneous values of meteor

The Mg II chromospheric emissions in cool stars were analyzed using high resolution IUE archive spectra. The ways in which interstellar (IS) absorptions can affect the shapes of the chromospheric profiles are discussed. It is possible to indicate regions of the sky where the Mg II IS absorption can be neglected, up to distances of a few tens of

We study how the regolith properties affect the measured fluorescent soft X-ray spectra from atmosphereless planetary surfaces as a function of mean particle size and particle size distribution, surface roughness and viewing geometry. The relative fluorescent elemental line intensities from the X-ray spectra measured from a planetary surface can be

Transiting extrasolar planets constitute only a small fraction of the range of stellar systems found to display periodic, shallow dimmings in wide-field surveys employing small-aperture camera arrays. Here we present an efficient selection strategy for follow-up observations, derived from analysis of the light curves of a sample of 67 SuperWASP

Aims:We aim to identify the nature of several objects previously catalogued as ultra-luminous X-ray (ULX) source candidates. Methods: Long-slit spectroscopy of the optical counterparts has been carried out. Results: The eight objects are at higher redshift than their putative parent galaxies. Conclusions: It is found that these eight previously