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The variation of galactic interstellar extinction in the ultraviolet.
Bohlin, R. C.; Witt, A. N.; Stecher, T. P.
The interstellar extinction in the UV (3.25 µm-1 ≤ λ-1 ≤ 8.0 µm-1) has been determined from IUE spectra for 29 reddened early-type stars by use of the pair method. The star sample was selected on the basis of highly deviant ratios of the strength of the 4430 Å diffuse interstellar absorption feature to …
The problem of the barium stars.
Bohm-Vitense, E.; Proffitt, C.; Nemec, J.
The authors report on ultraviolet observations of barium stars and other cool stars with peculiar element abundances. Those observations attempted to find hot white dwarf companions. Among six real barium stars studied, only ζ Cap was found to have a white dwarf companion. Among seven mild, or marginal, barium stars studied, at least three were fo…
Element depletions in interstellar gas - II. The density-dependence of calcium and sodium depletions.
Gondhalekar, P. M.; Pettini, M.; Phillips, A. P.
The behavior of Ca and Na depletions in interstellar gas is studied in view of complementary, high resolution optical and UV spectra for nine stars in the same region of sky. The optical absorption lines of Ca II and Na I are analyzed to determine their column densities in each line-of-sight, and the UV data are used to estimate H column densities…
Evidence for a high-temperature accretion region in Algol-type binarysystems.
Peters, G. J.; Polidan, R. S.
The recent discovery of strong absorption lines of N V, C IV, and Si IV in the UV spectra of Algol primaries, whose photospheric temperatures are much too cool to form such ions, has suggested the presence of a high-temperature component in the circumstellar matter in these systems. The authors have employed timed, high-resolution IUE observations…
K 648, the planetary nebula in the globular cluster M 15.
Howarth, I. D.; Seaton, M. J.; Walsh, J. R. +2 more
IUE observations of the planetary nebula K648 in the globular cluster M15 have been obtained, and the first determinations of the C abundance in the nebular envelope have been made. Improved measurements of fluxes in the optical nebular emission lines and in forbidden N II 6583 have been obtained. Semiforbidden C III 1908 and C II 2326 are strong …
The radial distribution of galactic gamma rays. II - The distribution of cosmic-ray electrons and nuclei in the outer galaxy
Caraveo, P. A.; Bignami, G. F.; Strong, A. W. +7 more
In the present derivation of the radial distribution of high energy gamma-ray emissivity in the outer Milky Way, the kinematics of H I are used to construct column-density maps in various galactocentric distance ranges that are then used in combination with COS-B spacecraft gamma-ray data to determine emissivities in these distance ranges. The res…
VW HYI : the white dwarf revealed.
Szkody, P.; Mateo, M.
Nonsimultaneous IUE, optical, and near-IR observations of VW Hyi at quiescence are presented. Using these and UV data from other investigations, a broad feature in the ultraviolet is identified with L-alpha absorption. The presence and width of the line imply that (1) the white dwarf in VW Hyi is directly visible in the UV and (2) the effective te…
Observations of Nova MUSCAE 1983 from 1200 A-10 mu-m during its earlydecline stage.
Leitherer, C.; Beuermann, K.; van Paradijs, J. +8 more
Spectroscopic and photometric observations of Nova Mus 1983 were carried out during its early decline phase over a wide spectral range from 1200 A to 10 microns, and the results are presented. Nova Mus 83 was a moderately fast to fast nova whose probable maximum brightness and lifetime were roughly 7 mag and 40 days. A distance of 4.8 + or -1 kpc …
IUE observations of DQ Herculis and its nebula, and the nature of thecold nova shells.
Gondhalekar, P. M.; Lambert, D. L.; Shields, G. A. +4 more
The nebula ejected in the 1934 outburst of the classical nova DQ Her is remarkable for its unprecedentedly low temperature of Te 500 K as measured by Williams et al. (1978). In this paper, IUE observations are combined with Steward optical spectra. It is confirmed that the gas is quite cold. It is further shown that the gas is ionized by the radia…
Multifrequency observations of the BL Lacertae object 0735 +178.
Rieke, G. H.; Pollock, J. T.; Huggins, P. J. +18 more
Four simultaneous spectra covering the radio through the X-ray regimes were made between 1979 October and 1981 March of the variable BL Lac object 0735+178. In each spectrum, the IR-UV synchrotron continuum dominates the total observed power (1047 ergs s-1) and presumably becomes opaque between 1011 and 1013