Search Publications
Missions
Journals
Publication Years
Ultraviolet variability of the Seyfert 1 galaxy Fairall 9
Clavel, J.; Rodriguez-Pascual, P. M.; Wamsteker, W. +5 more
The large amplitude of the variations of the Seyfert I Galaxy Fairall-9 between 1978 and 1991 make this Active Galaxy especially suitable for a combined study in terms of reverberation analysis and photoionization modeling over the velocity field of the broad lines of its ultraviolet spectrum. We have combined our ultraviolet data with those avail…
The Ultraviolet Extinction Curve for Circumstellar Dust Formed in the Hydrogen-Poor Environment of V348 Sagittarii
Clayton, Geoffrey C.; Drilling, John S.; Hecht, James H. +3 more
New International Ultraviolet Explorer (IUE) spectra with high signal-to-noise ratios have been obtained during the recovery of the hot R Coronae Borealis star, V348 Sgr, from its 1992 minimum. These spectra have been combined with spectra from the IUE archives to obtain a definitive extinction curve for dust recently ejected from this star, and m…
Contemporaneous IUE, EUVE, and High-Energy Observations of 3C 273
Kafatos, M.; Bruhweiler, F. C.; McHardy, I. M. +5 more
We present the results of our 1994 January and 1995 January observations of the quasar 3C 273 obtained with the International Ultraviolet Explorer (IUE) and the Extreme-Ultraviolet Explorer (EUVE). These observations were part of a large multiwavelength campaign to observe 3C 273 from radio through γ-rays. Our 1995 January photometric observations…
Detection of β Pictoris-like Gaseous Infall in 2 Andromedae
Neff, James E.; Cheng, K. -P.; Bruhweiler, Fred C.
Ultraviolet observations of 2 Andromedae with the Goddard High Resolution Spectrograph on board the Hubble Space Telescope (HST) clearly reveal the existence of circumstellar gas, in addition to previously known anomalous interstellar features, in the line of sight toward this nearby star. We also detect varying, redshifted Ca II absorptions, whic…
Cosmic ray modulation in a non-spherical heliosphere during solar minimum conditions
Potgieter, M. S.; Haasbroek, L. J.
It is expected that the position of the modulation boundary in the equatorial and polar regions of the heliosphere depends on solar activity and possibly also on the polarity of the heliospheric magnetic field. In general, it can be assumed that the changing outward solar wind pressure causes a dynamic boundary position. Since the solar wind plasm…
An Analysis of the Statistics of the Hubble Space Telescope Kuiper Belt Object Search
Brown, Michael E.; Kulkarni, Shrinivas R.; Liggett, Timothy J.
We calculate statistical limits to the detection of Kuiper belt objects in the Hubble Space Telescope (HST) data of Cochran et al., in which they report the discovery of a population of Halley-sized objects in Pluto-like orbits. Detection of a population of faint objects in these data is limited by the number of false objects that appear owing onl…
Restoration of Long-Exposure Full-Disk Solar Intensity Images
Duvall, T. L.; Jefferies, S. M.; Toner, C. G.
We describe an algorithm for restoring full-disk solar intensity images blurred by a smooth, quasi-stationary point-spread function (PSF). For Earth-based observations, this type of data can be obtained by using exposure times that are much longer than the redistribution time of the atmosphere. Using simulated data for a wide range of observing co…
The Age of the Globular Cluster M68
Castellani, V.; Brocato, E.; Piersimoni, A.
Relying on the accurate color-magnitude diagram (CMD) presented by Walker in 1994, we use the fitting of moderately hot horizontal-branch models to the observed CMD to derive suitable information regarding both cluster reddening and distance modulus and to discuss theoretical predictions constraining the absolute age of the metal-poor Galactic glo…
The Mass of the Classical Cepheid V350 SGR
Bohm-Vitense, E.; Evans, N. R.; Carpenter, K. +2 more
Two medium resolution spectra of the hot companion of the Cepheid V350 Sgr have been obtained with the Goddard High Resolution Spectrograph aboard the Hubble Space Telescope. Comparison of these spectra (in the wavelength range 1840 to 1880 \AA) with the spectrum of $\alpha$ Lyr shows that V350 Sgr B has a projected rotation velocity which may be …
Infrared Photometry of 487 Sources in the Inner Regions of NGC 5128 (Centaurus A)
Minniti, Dante; Alonso, M. Victoria
We study the sources present in the inner 3 kpc region of NGC 5128 (Cen A), most of which are star clusters of different ages. Photometry of archival Hubble Space Telescope WFPC images (F675W filter) is complemented with IR photometry (JHK' filters) obtained with the IRAC2B infrared array camera at the ESO/MPI 2.2 m telescope. From IR color maps w…