We quantify the energy radiated through all the collisional lines in a photoionized nebula in the presence of temperature fluctuations in the form of hot spots caused by an unknown heating process. The excess energy radiated in the lines as a result of the fluctuations is found to scale linearly with their mean-square amplitude t2. We find that the

We have analysed short-exposure high-resolution images obtained on the William Herschel Telescope (WHT), Big Telescope Azimuthal (BTA) and Canada-France-Hawaii Telescope (CFHT) in order to investigate mechanical vibrations that are capable of reducing the high angular resolution allowed by speckle-interferometric methods. After filtering the photon

Searching for subtle dips in brightness is all the rage among astronomers seeking Earthlike planets beyond the solar system.

We present a study focusing on the nature of compact groups (CGs) through the study of their elliptical (E) galaxies. Parameters describing the internal dynamics and the stellar populations of the galaxies are compared with their counterparts in other environments. Our sample has 24 bright E galaxies located in the core of Hickson CGs and 11 bright

We report here on the discovery of supersonic Evershed downflows in the penumbra of a sunspot. These flows are shown to occur along spatially unresolved, very cold magnetic flux tubes whose downflowing footpoints are found from the middle penumbra outward. Evershed flows along magnetic field lines returning to the solar surface were discovered by

Near-infrared (JHK) images of the nucleus of the barred spiral galaxy M100 (NGC 4321) have been obtained using a high-bandwidth tip-tilt secondary and fast guider system on the 3.8 m United Kingdom Infrared Telescope (UKIRT). The resulting images, with a resolution of 0.34'' at K, reveal for the first time a host of compact `knots', which appear to