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Coordinated UV and optical observations of the AM Herculis object E 1405-451 in thehigh and low sta
Maraschi, L.; Tanzi, E. G.; Motch, C. +5 more
Simultaneous UV and optical observations of the magnetic white dwarf binary E1405-451 taken in February 1983, March, and April are reported. In March the source was found in a low state analogous to those observed in AM Her. In this state the ultraviolet spectrum of E1405-451 can be interpreted as the emission from a hot white dwarf/T = 26,500 K, …
Ultraviolet observations of interstellar extinction near the Cepheus OB3 molecular cloud.
Savage, B. D.; Massa, D.
IUE data are used to derive UV extinction curves for O and B stars in the Cep OB3 association. These data are analyzed in conjunction with ANS photometry of additional association stars. While the level of the far-UV extinction differs greatly throughout the region the shape of the 2175 Å bump does not. The authors demonstrate that the different c…
LSS 4300 : a hot counterpart of upsilon Sagittarii and KS Persei ?
Drilling, J. S.; Schoenberner, D.
A number of recent observations indicate that the star LSS 4300 (HDE 320156) is a high-temperature analog of the hydrogen-deficient binaries Upsilon Sgr and KS Per. A preliminary model-atmosphere analysis based on high dispersion spectra obtained at Kitt Peak and Cerro Tololo yields Teff = 14,400 K, log (g) = 1.4, n(H)/n(He) = 0.003, and n(N)/n(C)…
Images in the rocket ultraviolet : photometry of M 101.
Bohlin, R. C.; Stecher, T. P.; Hill, J. K.
Three ultraviolet images of the Sc I galaxy M101 (NGC 5457) were obtained by a rocket-borne telescope, using a microchannel plate image intensifier coupled to IIa-O film, giving an effective wavelength of 2250 Å, a bandpass of 970 Å, and about 10arcsec resolution over an 80arcmin field. Extreme Population I dominates in the UV in the form of OB/H …
IUE spectrophotometry of the DA4 primary in the short-period white dwarf red dwarf spectroscopic binary Case 1.
Sion, E. M.; Wesemael, F.; Guinan, E. F.
Low-resolution ultraviolet International Ultraviolet Explorer spectra of the DA white dwarf Case 1 are presented. The spectra show the presence of the 1400 A feature, already discovered in several other DA stars, and of a shallower trough in the 1550-1700 A range. A model atmosphere analysis of the ultraviolet energy distribution of the Ly-alpha r…
X-ray and UV observations of two radio-bright quasars.
Elvis, M.; Fabbiano, G.
The two quasars PKS 10004 + 13 (4C 13.41, V about equal to 15.2, z = 0.140) and PKS 0637 - 75 (V = 15.75, z = 0.651) were observed in December 1980 with IUE. Both were detected in the short-wavelength region. The present X-ray upper limit for PKS 1004 + 13 gives the lowest L-x/L-opt measured in quasars. PKS 0637 - 75 was observed nearly simultaneo…
Multigrequency spectral behavior of the BL Lacertae objects OI 90.4 and 3C 66A.
Bruhweiler, F. C.; Miller, H. R.; Worrall, D. M. +4 more
Single-epoch multifrequency data for the BL Lac objects OI 90.4 and 3C 66A, spanning radio through ultraviolet wavelengths, are presented, as well as other measurements relevant to intensity and spectral-shape variability. Both BL Lac objects exhibit spectral curvature in the infrared-to-ultraviolet region, a properity that is inferred to be usual…
On the dispersion in brightness of far-ultraviolet emission lines of cool giant stars.
Simon, T.
Low-resolution spectra have been obtained with the short-wavelength camera of IUE for late-type giant stars of spectral type F5 III-G8 III. These stars are believed to be in their first crossing of the H-R diagram, as inferred from their location along the blue edge of the Hertzsprung gap or their high abundance of lithium. From the earliest spect…
Rotational modulation of the chromospheric activity in KHI 1 Orionis (GO V).
Simon, T.; Boesgaard, A. M.
The solar type star χ1 Ori is thought to have an age of 6×108yr and an apparent rotation period of 5d.1. These characteristics make it well suited for a rotational modulation study of its strong ultraviolet emission lines. The authors have made IUE observations at four different phases during each of three separate…
Multifrequency observations of the BL Lacertae objects OQ 530 and ON 325.
Bruhweiler, F. C.; Miller, H. R.; Sitko, M. L. +10 more
Spectral measurements of the two BL Lac objects OQ 530 and ON 325 are presented. The measurements were taken at frequencies ranging from radio to ultraviolet. Both sources show spectral curvature between the infrared and ultraviolet frequencies. The intensity and spectral shape of OQ 530 vary, but the spectral shape of ON 325 appears to remain con…