Analyses of the near-ultraviolet continuum of late-type stars have led to controversial results regarding the performance of state-of-the-art model atmospheres. The release of the homogeneous International Ultraviolet Explorer (IUE) final archive and the availability of the high-accuracy Hipparcos parallaxes provide an opportunity to revisit this

A long flux enhancement, with an exponential decay time of 86 min, is detected in 4U 1735-44 with the BeppoSAX Wide Field Cameras. We argue that this is a type I X-ray burst, making it the longest such burst ever observed. Current theories for thermonuclear bursts predict shorter and more frequent bursts for the observed persistent accretion rate.

Multiple shell planetary nebulae (MSPNe) are those which, in addition to the main bright inner shell, show one or two additional external shells. These faint external shells often have aspherical geometries, indicating an interaction with the surrounding interstellar medium (ISM). Our aim is to investigate, first of all, if the current theoretical

The High Altitude Observatory of the National Center for Atmospheric Research (HAO/NCAR) in collaboration with the Instituto de Astrofísica de Canarias (IAC) have recently completed a two-station helioseismic network with sites at Mauna Loa, Hawaii and Izana, Tenerife. The instruments are Doppler imagers employing Magneto-Optical filters and are

When the Reynolds number is not small, the wake trailing a buoyant magnetic flux tube sheds vortex rolls therefore producing a Von Karman vortex street and an imbalance of vorticity in the tube which results in a transverse oscillation of the tube as a whole. The actual path followed by the magnetic structure is therefore directly affected by the

The ISO coronal line spectrum of a sample of the brightest known Seyfert galaxies is presented and modeled. ISO observations of [O IV] 25.9 μ, [Ne V] 14.3 μ, [Mg VIII] 3.02 μ and [Si IX] 2.58 μ lines are presented; their relationship with the ionizing spectrum from 50 to 300 eV is investigated. Pure photoionization models reproduce the line ratios