Search Publications
The Southern Proper Motion Program. I. Magnitude Equation Correction
Kozhurina-Platais, Vera; Girard, Terrence M.; van Altena, William F. +2 more
As with virtually all photographic plate material, the astrograph plates from which the Southern Proper Motion (SPM) catalog is being compiled suffer from magnitude-dependent systematic shifts in the image positions, i.e., a magnitude equation. If left uncorrected, these would adversely affect both the primary goals of the SPM catalog, the absolut…
The Optical Spectrum of the Planetary Nebula NGC 2440
Hyung, Siek; Aller, Lawrence H.
Wavelengths and identifications have been provided for approximately 300 lines between 3660 and 10125 Å in the spectrum of the bipolar planetary nebula NGC 2440. These lines measured with the Hamilton echelle spectrograph at Lick Observatory and supplemented by published IUE results are used to construct diagnostic diagrams and derive ionic concen…
Random Damping and Frequency Reduction of the Solar F Mode
Kosovichev, A. G.; Murawski, K.; Duvall, T. L., Jr.
We present observations showing that the frequency of the high-degree f-mode is significantly lower than the frequency given by the simple dispersion relation, ω2=gk , and that the line width grows with the wavenumber k. We attempt to explain that this behavior is the result of the interaction with granulation, which we model as a rando…
Differences between the Optical/Ultraviolet Spectra of X-Ray Bright and X-Ray Faint QSOs
Green, Paul J.
We contrast measurements of composite optical and ultraviolet (UV) spectra constructed from samples of QSOs defined by their soft X-ray brightness. X-ray bright (XB) composites show stronger emission lines in general, but particularly from the narrow-line region. The difference in the [O III]/Hβ ratio is particularly striking, and is even more so …
Tomographic Analysis of Hα Profiles in HDE 226868/Cygnus X-1
Shafter, A. W.; Gies, D. R.; Bagnuolo, W. G. +3 more
We present high-quality Hα spectra of the massive X-ray binary HDE 226868 = Cyg X-1 that were made in 1985 and 1986. We measured radial velocities using the He I λ6678 line, and we use the resulting orbital solution together with a Hipparcos light curve of the ellipsoidal variation to arrive at a revised period estimate of P = 5.59977 +/- 0.00002 …
Hubble Space Telescope Observations of an Accreted Silicon SPOT on the White Dwarf in V471 Tauri
Bond, Howard E.; Sion, Edward M.; Saffer, Rex A. +2 more
We have used the Hubble Space Telescope's (HST) Goddard High-Resolution Spectrograph to detect a photospheric metallic absorption line, Si III λ1206, in the spectrum of the magnetic white dwarf component of the Hyades precataclysmic binary V471 Tauri. The Si III feature is modulated on the soft X-ray/EUV/optical 9.25 minute rotational period of th…
Starcounts in the flanking fields of the Hubble Deep Field. The faint end of the disc stellar luminosity function and its scale-height
Mendez, R. A.; Guzman, R.
We present instrumental (F606W, F814W) and calibrated (V, I) photometry and astrometry for point-like sources in the Hubble Deep Field and its flanking fields from combined HST and Keck direct imaging. From this data, a complete sample of stars in the range 18 <= V ~ 25 is derived and compared to the predictions of a galactic structure model. T…
Galaxy Morphology from NICMOS Parallel Imaging
Gardner, Jonathan P.; Teplitz, Harry I.; Heap, Sara R. +1 more
We present high-resolution Near-Infrared Camera and Multiobject Spectrometer images of random fields obtained in parallel to other Hubble Space Telescope observations. We present galaxy number counts reaching H1.6=24. The H1.6-band galaxy counts show good agreement with the deepest I- and K-band counts obtained from ground-ba…
ISO LWS Observations of Cool Evolved Stars and Post-AGB Objects
Barlow, M. J.
Ultraviolet and Optical Studies of Binaries with Luminous Cool Primaries and Hot Companions. V. The Entire IUE Sample
Parsons, Sidney B.; Ake, Thomas B.
We have obtained or retrieved IUE spectra for over 100 middle- and late-type giant and supergiant stars whose spectra indicate the presence of a hot component earlier than type F2. The hot companions are classified accurately by temperature class from their far-UV spectra. The interstellar extinction of each system and the relative luminosities of…