Search Publications
Does SV Centauri Harbor an Accretion Disk?
Linnell, Albert P.; Scheick, Xania
Light synthesis simulation of SV Cen UBV photometry by Drechsel et al. (1982) exhibits appreciable residuals. These residuals, together with large Roche model overcontact but also large calculated intercomponent temperature difference, suggests that the light synthesis Roche model is inapplicable. The substantial rate of period change indicates ra…
First Results from the Goddard High-Resolution Spectrograph: Ultraviolet Spectra of a Starburst Knot in NGC 1068
Hutchings, J. B.; Bruhweiler, F.; Boggess, A. +7 more
We present UV spectroscopy of a circumnuclear starburst knot in the Seyfert 2 galaxy NGC 1068. The spectrum shows the presence of several thousand O and B stars which appear to have formed about 3 million years ago. We also discuss the extinction and interstellar medium in the line of sight.
Observations That Link Infrared Cirrus and Ultraviolet Extinction
Tapia, Mauricio; Hecht, James H.; Hackwell, John A.
Results are presented of UV extinction measurements of 17 stars in the open cluster IC 4665 and of four stars in the open cluster NGC 1647, showing that the UV extinctions of the two clusters stars have different properties. Whereas the stars in NGC 1647 cluster are typical of general interstellar space, the stars in IC 4665 have a small 'linear' …
The luminosity of the B2 hypergiant HD 80077.
de Jager, C.; Nieuwenhuijzen, H.; Carpay, J.
The extremely bright and relatively stable hypergiant HD 80077 is an enigmatic object. Since the star is assumed to have a luminosity of 2 x 10 exp 6, considerable variability and a large mass loss rate would be expected. However, its mass loss rate of (5 +10/-3) x 10 exp -6 solar mass/yr and its variability are very low with respect to its lumino…
Faint Object Camera Observations of a Globular Cluster Nova Field
Anderson, Scott F.; Jakobsen, Peter; Bohlin, Ralph C. +2 more
The Faint Object Camera onboard Hubble Space Telescope has obtained U and B images of the field of Nova Ophiuchi 1938 in the globular cluster M14 (NGC 6402). The candidate for the quiescent nova suggested by Shara et al. (1986) is clearly resolved into at least six separate images, probably all stellar, in a region of 0.5 arcsec. Although two of t…
Sulfur-bearing Ions in the Ionosphere of Comet Halley
Reme, H.; Korth, A.; Lin, R. P. +3 more
This paper presents the radial density profiles of the ions corresponding to 35, 45, 47, and 47 amu, inside the ionopause of Comet Halley, obtained by the heavy ion analyzer PICCA on board the Giotto spacecraft. A photochemical model of the outflowing atmosphere/ionosphere, which emphasizes the sulfur chemistry in an H2O-dominated atmosphere, is u…
Quasr link conditions for Hipparcos.
Ducourant, C.; Brosche, P.; Geffert, M. +2 more
Fictitious proper motions of quasars and of their surrounding stars have been determined based on plates with epoch differences of up to 90 yrs. From the fact that the true proper motions of the quasar are vanishingly small, we obtain conditions for the extragalactic calibration of the preliminary Hipparcos system. We present results for the field…
UV Observations of the Cool DBQA5 White Dwarf LDS 678A: Limits on the Atmospheric Composition, Pressure Shift, and Gravitational Redshift Derived from C I 2479
Sion, Edward M.; Koester, Detlev; Liebert, James W. +5 more
A high-resolution ultraviolet spectrum of the helium-rich degenerate LDS 678A, obtained with the International Ultraviolet Explorer (IUE) satellite, is presented. LDS 678A is the coolest metallic line degenerate (DQ or DZ) yet observed with the IUE echelle. These observations provide a detailed line profile of the strong C I 2479 absorption line a…
IUE observations of the quasar 3C263 constrain the ionizing photon luminosity of decaying dark matter.
Fabian, A. C.; Naylor, T.; Sciama, D. W.
Dark matter which produces hydrogen-ionizing photons on a time-scale of 2x1023s has been shown by Sciama to explain many problems in astronomy and cosmology. Clusters of galaxies composed of such dark matter will be luminous sources of ionizing photons. The authors report here the results of a search for an otherwise unidentified, exten…
On the Utility of Low Resolution IUE Spectroscopy of the 2800 A MG II Lines as a Stellar Chromosphere Indicator
Smith, Graeme H.; O'Connell, Robert W.; Burstein, David +2 more
Low resolution IUE spectroscopy of the 2800-A Mg II h and k lines is shown to provide a useful means for documenting chromospheric activity among relatively young dwarf stars. An index I(Mg II) has been defined which measures the integrated flux in the region 2784-2814 A relative to the flux interpolated from nearby comparison regions. Values of t…