Search Publications
Missions
Journals
Publication Years
The X-ray modulation of CYG X-3.
van der Klis, M.; Bonnet-Bidaud, J. M.
Results of three 40d COS-B X-rays observations of Cyg X-3 are presented. The shape of the light curve, although variable from cycle to cycle, is generally very stable when averaged over many cycles. During one four-week period, however, a different mean light curve was observed. It is shown that the correlated behavior of amplitude, average level,…
Long term X-ray observations of SMC X-1 including a turn-on.
van der Klis, M.; Bonnet-Bidaud, J. M.
A 38 d COS-B observation of SMC X-1 in the 2-12 keV band is presented, the observation including a turn-on of this source. The data are analyzed within the framework of the stellar wind accretion model, both from the point of view of the expected accretion rate and of the absorption of X-rays in the wind. It is noted that neither the high state lu…
Ultraviolet extinction curves derived from IUE data.
Joseph, C. L.; Snow, T. P., Jr.; Seab, C. G.
Data from the International Ultraviolet Explorer (IUE) have been used to derive extinction curves for several stars chosen because of unusual diffuse band strength or location within dense clouds. Both the strength and position of the 2200 A extinction maximum were assessed, as well as the level of extinction in the far-ultraviolet. A variety of c…
BE UMa (PG 1155+492) : a unique cataclysmic-variable-like object.
Spinrad, H.; Green, R. F.; Liebert, J. +2 more
The variable spectrum of BE Ursae Majoris, which is similar to that of the cataclysmic variables (CVs), shows (1) an emission-line spectrum with the high-excitation CN 4650 A blend as the strongest optical feature, weaker H and He lines, and a strong Balmer jump, and (2) an absorption spectrum dominated by He. Although the object shows no evidence…
The ultraviolet spectrum of the magnetic degenerate star GD 229.
Green, R. F.; Liebert, J.
The ultraviolet spectrum obtained with the IUE satellite of the magnetic degenerate white dwarf star GD 229 is presented. The ultraviolet energy distribution measured by the short- and long-wavelength cameras covering the range 1170-3200 A, when combined with optical data, indicates a best fit blackbody temperature of 16,000 K, which is significan…
The ultraviolet interstellar extinction curve in the Pleiades.
Bohlin, R. C.; Witt, A. N.; Stecher, T. P.
The wavelength dependence of ultraviolet extinction in the Pleiades dust clouds has been determined from IUE observations of HD 23512, the brightest heavily reddened member of the Pleiades cluster. There is evidence for an anomalously weak absorption bump at 2200 A, followed by an extinction rise in the far ultraviolet with an essentially normal s…
3C273 - a Review of Recent Results
Ulrich, M. -H.
3C 273 is the most extensively studied quasar both from the ground and from space. Recent satellite observations have given important information on the overall electromagnetic spectrum of 3C 273 in the γ-ray, X-ray, and UV ranges. The most salient results are: (i) the energy per decade of frequency emitted by 3C 273 is nearly constant between 600…
Quasi-simultaneous observations of BL Lac object MRK 501 in X-ray, UV, visible, IR, and radio frequencies.
Kondo, Y.; Yee, H. K. C.; Worrall, D. M. +8 more
Observations in the X-ray, UV, visible, IR and radio regions of the BL Lac object Mrk 501 made over the course of two months are reported. The measurements were made with the A2 experiment on HEAO 1 (X-ray), the SWP and LWR cameras on IUE (UV), the 5-m Hale telescope (visible), the 2.5-m telescope at Mount Wilson (IR), the NRAO 92-m radio telescop…
The dwarf nova Z Cha. II. Spectroscopy.
Rayne, M. W.; Whelan, J. A. J.
Spectroscopic observations are presented of Z Cha in quiescence. The data include moderate spectral resolution scans over the greater part of an orbit and with high time resolution through eclipse. Also discussed are various lower resolution spectra and UV and optical spectrophotometry. The spectrum is found to be dominated by broad double peaked …
The variable shell star HR 5999 : V. The spectral energy distribution.
Liseau, R.; Wamsteker, W.; The, P. S. +10 more
From April to August 1978 an international campaign was organized to observe the variable shell star HR 5999 with different techniques. A study of part of the collected material yields the following results. The visual light variation follows the general pattern as found at earlier observations ; the star stays usually long around maximum brightne…