A periodic signal of high nominal significance (99.95%) is found in the light curve of OJ 287 in observations taken with the Prime Focus Camera Unit on the 2.5 m Isaac Newton Telescope on two nights in March April 1987. No such periodicity is seen in the light curve of the simultaneously observed reference star. A null test involving observations

The results of near-infrared mapping, optical spectroscopy, and millimetric CO J = 2-1 observations of the halo about IC 418 are presented. As a result, it is confirmed that NIR emission extends outside of the principal emission shell, and into a zone characterized by weak optical grain scattering and (in all probability) strong FIR emission. An

Theoretical models are developed to account for the asymmetries observed by Stenflo et al. (1984) in the Stokes V profiles of solar faculae. The approximate dependence of Stokes V on magnetic and velocity fields in the line of sight is characterized under the assumption of local thermodynamic equilibrium, and empirical growth curves for the zero

A total of over 210 hr of previously unpublished differential photoelectric photometry of 21 Com (HD 108945, HR4766), obtained in five years, were analysed to search for periodicities. Of these, the 88 hr obtained in 1983, 1985, 1986 and 1989 were searched for, and show no indications of short-period variability. In 1988, over 116 hr of

The new observational O/Fe vs Fe/H relationship in halo dwarfs is analyzed in terms of a model of chemical evolution for the solar neighborhood. The role of nucleosynthesis prescriptions for SN II and SN I (both Ia and Ib) is analyzed. It is shown that, by adopting iron yields for SN II according to the observations of SN 1987A and by assuming

Deep spectra of the planetary nebula IC 418 were obtained in the wavelength range 4190-5850 A. The data made it possible to map an extended halo about the source, evaluate the variation in halo intensity with radius, and model the results in terms of a radially symmetric dust scatter envelope. It is suggested that the nebula is in a relatively