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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…
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…
On the ultraviolet iron spectrum of pre-white dwarfs.
Drilling, J. S.; Schoenberner, D.
The authors have detected numerous lines of Fe V, Fe VI, and Fe VII in high-resolution IUE spectra of two central stars and a number of very hot subdwarfs. The strengths of these lines vary widely from star to star, suggesting that the abundance of iron in the atmospheres of the immediate progenitors of white dwarfs in strongly variable. A possibl…
KPD 0005+5106 : a post-PG 1159 type object ?
Margon, B.; Downes, R. A.; Liebert, J.
In a survey for galactic plane UV-excess objects, a very hot (T about 100,000 K) helium-rich white dwarf is discovered. The object is spectroscopically similar to the pulsating PG 1159 class of stars, with narrow emission lines of He II, probably C IV, and possibly C III/N III, although there is no trace of carbon absorptions. Not all features hav…
A search for diffuse interstellar bands in the ultraviolet.
Snow, T. P., Jr.; Seab, C. G.
The International Ultraviolet Explorer (IUE) Satellite was used to collect interstellar extinction curves for 58 moderately reddened lines of sight. Spectral types of the background stars ranged from O7 to A0. All luminosity classes are represented, but early B main-sequence stars predominate. E(B-V) reddening values ranged from 0.14 to 1.13 mag, …
IUE results on the AM Herculis stars CW 1103, E 1114 and PG 1550.
Szkody, P.; Panek, R. J.; Liebert, J.
IUE data are presented on three AM Her stars (CW 1103 + 254, E1114 + 182, and PG 1550 + 191) which are used in conjunction with optical and IR fluxes to study the accretion characteristics of these systems in relation to other polars.The time-resolved IUE spectra of CW 1103 show that the column contributes little to the UV, while the white dwarf, …
The galactic gamma-ray distribution - Implications for galactic structure and the radial cosmic-ray gradient
Harding, A. K.; Stecker, F. W.
The radial distribution of gamma ray emissivity in the Galaxy was derived from flux longitude profiles, using both the final SAS-2 results and the recently corrected COS-B results and analyzing the northern and southern galactic regions separately. The recent CO surveys of the Southern Hemisphere were used in conjunction with the Northern Hemisphe…
Analysis of ultraviolet atmospheric eclipses in the Wolf-Rayet binaryCV Serpentis.
Cherepashchuk, A. M.; Eaton, J. A.; Khaliullin, Kh. F.
The authors have obtained ultraviolet spectra covering one-half of an orbital cycle of CV Ser. Marked phase effects have been detected in which ultraviolet absorption lines are greatly strengthened when the W-R star is in front. No eclipses are seen longward of 2300 Å, while below 2000 Å blanketing by numerous lines, spread out in frequency by the…