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Optical positions of radiostars. II.
Costa, E.; Loyola, P.
Precise optical positions, relative to either the Perth 70 or the AGK3R catalogs, have been obtained for 40 radiostars proposed to the Hipparcos observing list. Precision levels between 0.18 and 0.29 arcsecs were obtained.
Ultraviolet Spectra of Field Horizontal Branch A-Type Stars. II.
Adelman, Saul J.; Philip, A. G. Davis; Hayes, D. S.
The spectra of six additional A-type stars have been obtained at low resolution between 1200 and 1900 A with the IUE. The energy distributions of four of the stars match that of the field horizontal branch (FHB) distribution in Huenemoerder et al. (1984) while those of the other two do not. Three of the FHB stars fall above a line in the C(19 - V)…
The ultraviolet spectrum of the hydrogen-poor binary HD 30353.
Hack, M.; Parthasarathy, M.; Tektunali, G.
An analysis is made of the high- and low-resolution UV spectra of the hydrogen-poor star HD 30353. The stellar wind profiles of the resonance lines of N V, C V, and Si IV are found to be similar to those observed in Upsilon Sgr. However, HD 30353 shows shortward-shifted profiles also in the ground-level lines of Fe II, in the subordinate multiplet…
Multifrequency Observations of the Optically Active Radio-quiet Quasar GQ Comae. I. Ultraviolet Continuum and Line Variability
Sitko, Michael L.
This paper summarizes the data and preliminary results of a 3 year project to monitor the continuum variability of GQ Com in the satellite ultraviolet and the associated variability of the Lyα and C IV lines. Simultaneous and nearly simultaneous ground-based optical and infrared data were also obtained, but these will be discussed more fully in a …
LTE analysis of the far-ultraviolet variations of 21 Comae.
Monier, R.; Megessier, C.
The far-ultraviolet variations of the cool Ap star 21 Com in the spectral region 1450 - 1510 A are studied by using synthetic spectra. The integrated flux of the star is calculated, and the effective temperature of the star is derived and found to be lower than previous estimates. The computation of synthetic spectra indicates that the flux at the…
Ultraviolet Gas Absorption and Dust Extinction toward M8
Bohm-Vitense, Erika; Boggs, Don
Interstellar absorption lines are analyzed using high-resolution IUE spectra of 11 stars in the young cluster NGC 6530 located in the M8 region. High-velocity clouds at -35 km/s and -60 km/s are seen toward all cluster stars. The components arise in gases that are part of large interstellar bubbles centered on the cluster and driven by stellar win…
The Spectroscopic Orbit of 6-DRACONIS
Reimers, D.; Griffin, R. F.; Eitter, J. J.
6 Dra has long been known to show small variations in radial velocity, and there is photometric and spectroscopic evidence that its spectrum is composite. We show, largely on the basis of a generous number of photoelectric radial velocities mainly obtained at Cambridge and Fick observatories, that the orbit is of mild eccentricity and has a period…
The comet nucleus: ice and dust morphological balances in a production surface of comet P/Halley.
Green, S. F.; McDonnell, J. A. M.; Pankiewicz, G. S. +2 more
Dust-to-gas mass ratios are presented based on in situ measurements of the coma dust and gas distributions of comet P/Halley by the DIDSY, PIA, and NMS experiments aboard the Giotto spacecraft. A relative excess, compared with preflight expectations, of particulates with masses >10-9kg is observed; if this is representative of the co…
The First UV Spectrum of a Uranian Satellite: IUE Observations of Oberon from 2650-3200 A
Buratti, B. J.; Stern, S. A.; Festou, M. C. +1 more
Using the International Ultraviolet Explorer (IUE) observatory, the first vacuum UV spectrum of Oberon was obtained. The data contain useful information in the spectral range 2650-3200 A. Oberon's UV geometric albedo is found to be flat and essentially featureless with an average value of p(UV) = 0.19 + or - 0.025, and making it possible to extend…
IUE Spectra of the Four Interacting Binary White Dwarf Stars - Am-Canum PG:1346+082 V803-CENTAURI and Gp-Comae - a Comparative Study
Solheim, J. -E.; Ulla, A. M.
This project is part of a world wide cooperation aimed at investigating properties of white dwarf stars to determine their constitution and evolution. The project is based on two recent developments: -The first is the discovery, of pulsational instabilities in some white dwarf stars, giving rise to non-radial pulsations which can be observed as fl…