We obtain the probability distribution for the volume of excursion sets in a three-dimensional Gaussian field, in order to develop the approximation to the cosmic mass function that follows directly from the assumption that the spherical collapse criteria may be applied to field points. We also use this distribution to develop an analytical

BDS 1269 is a visual binary system with a Delta Scuti star as the primary (Mechler, 1974) and a normal early F main sequence secondary BDS 1269B (HD 15164). Careful observations concerning the brighter primary in this system BDS 1269A (HD 15165, VW Ari) have been undertaken since its first finding by Mechler in 1974. Besides, an unpublished 8 night

This paper combines data from the three preceding papers in order to analyze the multi-wave-band variability and spectral energy distribution of the Seyfert I galaxy NGC 4151 during the 1993 December monitoring campaign. The source, which was near its peak historical brightness, showed strong, correlated variability at X-ray, ultraviolet, and

We have analyzed high spatial and spectral resolution Hα emission-line TAURUS data on two nearby giant H II regions, NGC 604 and NGC 588. Previous work shows that while NGC 604 is a relatively young system whose emission line kinematics is due to a combination of gravity and stellar wind-blown shells, NGC 588 seems more evolved, with its ionized

This paper presents the results of high speed photometric observations of the cool variable DA white dwarf (DAV) GD 154 obtained with the Whole Earth Telescope. GD 154 is one of the coolest pulsating DA white dwarfs and its study is important for understanding the red edge of the ZZ Ceti instability strip. Its power spectrum is dominated by three

We present optical and near-infrared spectroscopy (600-1000 nm) of eight faint (I > 18) very red (R - I > 2.2) objects discovered in a recent deep CCD survey of the Pleiades cluster by ZapateroOsorio, Rebolo, & Martin. We compare them with reliable cluster members like PP1 15 and Teide 1, and with several field very late type dwarfs (M4-M9.5)