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Bl-Lacertae Objects from the EXOSAT High Galactic Latitude Survey - Constraints on the Logn-Logs and on the Cosmological Evolution
Tagliaferri, G.; Beuermann, K.; Branduardi-Raymont, G. +8 more
Using a sample of 11 X-ray selected BL Lacertae objects extracted from the EXOSAT High Galactic Latitude Survey we derive the LogN-LogS relation of BL Lacs and we compare it with the results obtained with other X-ray surveys. All EXOSAT BL Lacs are characterized by featureless optical spectra and have been detected in the radio band. Excellent agr…
Evidence for the field line reconnection process in the particle and magnetic field measurements obtained during the Giotto-Halley encounter.
Neubauer, F. M.; Korth, A.; Daly, P. +5 more
Measurements of low (E = 250 - 1000 eV) and high (E = 60 to >300 keV) energy particles as well as the magnetic field obtained during the Giotto-Halley encounter on 13/14 March 1986 are used to study the field line merging process. Strong changes in the pitch angle distribution of energetic ions are observed simultaneously. The observations are …
Detection of a Strong Excess Noise Component in the Low State of 4U 1705-44
Hasinger, G.; Truemper, J.; Langmeier, A.
The timing analysis of four Exosat observations of the bright Galactic burst source 4U 1705-44 is presented. A correlation is found between the aperiodic noise components and the spectral variability. 4U 1705-44 shows in its low-intensity state a strong variability of the X-ray flux in the frequency range 1-64 Hz, corresponding to an rms modulatio…
A study of ultraviolet spectra of dzeta Aurigae/VV Cephei systems. XI. 22 Vulpeculae : IUE observations of its extended chromosphere and wind with spatial resolution.
Reimers, D.; Schroeder, K. -P.
A set of 18 high resolution IUE spectra of chromospheric-eclipse phases of 22 Vulpeculae are analyzed by means of growth curves. A density model is presented and the upper limit of the electron density is determined. Si II UV mult. 2 wind resonance lines at several phases are modeled with a two-dimensional transfer code. It is found that although …
Discovery of a Cool Expanding Shell at -1200 Kilometers per Second around V471 Tauri
Sion, Edward M.; Bruhweiler, Fred C.; Mullan, Dermott +1 more
High-resolution IUE spectra of V471 Tauri reveal the presence of a very-high-velocity cool expanding gas in the line of sight to the binary system with an expansion velocity of -1200 km/s. The summed strength of the coadded absorption is 125 mA + or - 25 mA, with FWHM = 30 km/s. It is suggested that the observed absorption may be related to the na…
Spectroscopic binary orbits from ultraviolet radial velocities. Paper 5: 29 (UW) Canis Majoris
Stickland, D. J.
Element identifications in IUE spectra of chemically peculiar stars :the Pt-Au-Hg sequence.
Fuhrmann, K.
The presence of the elemental sequence Pt-Au-Hg in IUE spectra of chemically peculiar and normal stars is discussed. The sample comprises the HgMn (= CP3) stars HR4072, HR7775, and Chi Lup; the Ap (= CP2) stars HR465 and Alpha2 CVn; and the normal stars Vega (A0V) and Nu Cap (B9V). UV lines of Pt II, Au II and Hg II are identified on IUE spectra f…
Intermediate resolution spectra of quasars with z>2.
Ulrich, M. -H.
20 quasars (optically selected) with redshifts in the range 2-2.7 have been observed with a spectral resolution of 7 A, for a statistical study of the properties of the emission lines and also to find interesting candidates for detailed studies. The distribution of the observed equivalent width (EW) of C IV is centered at 95 A and the distribution…
Discovery of a BL Lacertae object (EXO 055625-3838.6) in the error box of H 0557-385.
Tagliaferri, G.; Beuermann, K.; Giommi, P. +3 more
We present X-ray and optical data of a new BL Lacertae type object (EXO 055625-3838.6) which has been serendipitously discovered in an EXOSAT CMA image and is located within the error box of HO557-385 (4U0557-38, 3A0557-383), a hard X-ray source previously identified with a seyfert 1 galaxy. Although the soft X-ray flux of the BL Lac is 1O times h…
The First UV Spectrum of Triton: IUE Observations from 2600 to 3200 Angstrom
Skinner, T. E.; Stern, S. Alan; Trafton, L. M. +2 more
The results of the first observations of Triton's spectrum below 3300 A are reported. Triton's 2700 A geometric albedo is found to be 0.28 + or - 0.04. The albedo increases monotonically from 2600 to 3200 A, with a slope of 0.13 + or - 0.03 per 1000 A. This positive slope is qualitatively similar to, but shallower than, Triton's visible albedo slo…