David J. Westpfahl

Holmberg II - A laboratory for studying the violent interstellar medium

Original article can be found at: http://adsabs.harvard.edu/abs/ Copyright American Astronomical Society [Full text of this article is not available in the UHRA]

PHOTOMETRIC OBSERVATIONS OF X PERSEI

Published photometric observations of the variable star X Per from 1888 to the present are presented along with new monitoringat 1O time resolution. No activity is observed at the level over time intervals of hour. The long-term history shows some changes in photometric properties since the discovery of the objects variability, but no regular pattem is evident. Key words: variable stars - X-ray sources

The electrical properties of coal slag

Abstract The inorganic constituents of coal remaining after high temperature combustion in a MHD (Magnetohydrodynamic) power plant combustor form an iron-rich, “dirty” glass whose electrical properties are important in the operation of the MHD generator. In particular, alkali “seed” (K2CO3) is added to enhance the conductivity of the plasma so the slag layer which coats the walls and electrodes of the generator is rich in K2O. We present results of a systematic study of the electrical conductivity of a Rosebud coal ash with graded amounts of K2CO3 added. At high temperatures, the conductivity curves are smooth with many ions contributing. At lower temperatures the curves become more complex with the presence of crystalline phases in the glass.

A Survey for O-B Stars in the Puppis Window

In the 1950’s Haro (Haro and Luyten 1962) developed a survey method in which three images, roughly corresponding to U,B, and V, are exposed on one plate. The images are separated by several arc seconds by moving the telescope between exposures. Exposure times are chosen so an unreddened star of spectral type A0 to A5 shows three images roughly equal in size and density. The plates are examined by eye to find stars by their colors. A red star shows a strong central image flanked by two weaker images, while a blue star shows a weak central image flanked by two stronger ones. This method allows surveys for stars and galaxies with very red or very blue colors to be carried out with any telescope, and in particular with the Schmidt telescopes at Tonantzintla and at Palomar which were not equipped with objective prisms.