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UV and optical observations of variability in the WR+compact candidate HD 96548.
Smith, L. J.; Lloyd, C.; Walker, E. N.
The present IUE SWP high resolution spectra of the WR+ compact candidate HD 96548 exhibit significant variability in the P Cygni and emission line profiles. A reanalysis of previously published visible photometry in light of new data shows that all the photometry is periodic, with a period of 5.879 d or its one-day aliases at 0.855 and 1.204 d. Th…
The ultraviolet spectrum of the symbiotic star HM Sge.
Nussbaumer, H.; Mueller, B. E. A.
The authors present IUE fluxes of the symbiotic star HM Sge, extracted from IUE observations made during the years 1978 - 1983. They argue in favour of an accretion disc model. They suggest that the sudden flux increase in He II and the more highly ionized atoms were due to a decrease from a high mass accretion rate, leading to a luminosity above …
IUE observations of amorphous hot galaxies.
Hunter, D. A.; Lamb, S. A.; Gallager, J. S., III +1 more
Blue amorphous galaxies are star-forming, irregularlike systems which lack the spatially distinct OB stellar groups that are characteristic of most late-type galaxies. In order to better understand the nature of star-formation processes in these unusual galaxies, short-wavelength IUE spectra of the amorphous galaxies NGC 1705 and NGC 1800 have bee…
Closed coronal structures. VI. Far-ultraviolet and X-ray emission from active late-type stars and the applicability of coronal loop models.
Golub, L.; Peres, G.; Vaiana, G. S. +2 more
We present far-ultraviolet line fluxes of prominent transition region emission lines, as obtained with the International Ultraviolet Explorer satellite, for a sample of solar-type stars. We combine the ultraviolet observations with existing soft X-ray measurements obtained by the Einstein Observatory (HEAO 2). We utilize the resulting data set and…
On the nature of the UX Ursa Majoris-type nova-like variables : CPD -48 1577.
Sion, E. M.
A series of low-dispersion spectra and one high-dispersion spectrum have been obtained of the catacylsmic variable CPD-48 deg 1577. Like other UX UMa stars, this variable exhibits the flat continuum of a luminous, thick, steady state accretion disk dominating its light from the far UV to the infrared. A wind mass loss rate of less than about 10 to…
HD 160538 and HD 185510 : two active-chromosphere stars with hot companions.
Fekel, F. X.; Simon, T.
Short-wavelength ultraviolet spectra of two active-chromosphere giants, HD 160538 and HD 185510, show hot stellar continua and Lα absorption features. The hot companion of HD 160538 is a white dwarf whose ultraviolet spectrum is matched best to the energy distribution of a Teff = 30000K and log g = 8 model atmosphere. The ultraviolet sp…
Serendipitous EXOSAT sources in the region of the Coma cluster : active galactic nuclei with steep X-ray spectra.
Branduardi-Raymont, G.; Mason, K. O.; Martin, C. +1 more
A ≡7-hr observation of the central part of the Coma cluster of galaxies has been performed with the EXOSAT LE telescopes and CMA detectors. Five serendipitous sources are detected within the inner 35 arcmin radius of the field. Optical spectroscopy shows that four of these are background AGN not associated with the cluster. At the sensitivity leve…
The intrinsic ultraviolet continua of O stars.
Savage, B. D.; Massa, D.
Low-resolution IUE spectra of O and B stars in open clusters have been obtained. The main-sequence B stars are used to derive UV extinction curves for the program clusters, and these curves are used to determine the intrinsic UV to visual colors of O stars in NGC 2244, Trumpler 14, and NGC 6231. These data are analyzed in conjunction with the dere…
Detection of a compact companion of the mild barium star ksi1 Ceti.
Johnson, H. R.; Bohm-Vitense, E.
In the present paper, the observation of a white dwarf companion of the mild Ba star Xi-1 Ceti (= 65 Ceti = HR 649 = HD 13611) is reported, taking into account also the properties of the mild Ba star and of its companion. The UV spectrum of Xi-1 Ceti is discussed along with an interpretation of this spectrum. Attention is given to the effective te…
Dwarf novae in outburst : simultaneous ultraviolet and optical observations of RU Pegasi and TZ Persei.
Verbunt, F.; Schwarzenberg-Czerny, A.; Jones, D. H. P. +6 more
The authors present ultraviolet and optical observations of the dwarf novae RU Peg and TZ Per during decline from outburst. In both systems the flux drops simultaneously at all wavelengths. In TZ Per the flux distributions during standstill and during the decline from different outbursts are similar. The authors discuss briefly the implications of…