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Simultaneous X-Ray, Ultraviolet, and Optical Observations of LMC X-3
Maraschi, L.; Tanzi, E. G.; Belloni, T. +7 more
The black hole candidate LMC X-3 was observed simultaneously at X- ray (Ginga), UV (IUE), and optical frequencies in 1988 January. The X- ray energy distribution is the superposition of a thermal component and a hard tail. The former component can be described equally well by a Comptonization spectrum or by a disk blackbody. In the latter picture,…
Raman scattering as a diagnostic tool in the massive X-ray binary 4U1700 - 37
Hammerschlag-Hensberge, G.; Kaper, L.; Takens, R. J.
HD153919, an extreme Of star (spectral type O6.5Iaf+; ref. 1) has been identified as the optical counterpart of the 3.411-day eclipsing massive X-ray binary 4U1700 - 37 (ref. 2) by spectroscopic3-5 and photometric6 studies which revealed periodic optical variations in phase with the X-ray period. Here we report tha…
Ultraviolet Observations of NGC 205
Bertola, Francesco; Wilcots, Eric M.; Hodge, Paul +2 more
Low-resolution IUE observations of the dwarf elliptical galaxy NGC 205 show that the UV spectral energy distribution of the galaxy is relatively flat. Spectra centered on the nucleus and on a region north of the nucleus show evidence of recent "bursts" of star formation which contribute strongly to the UV spectral energy distribution. We fit the U…
Effective temperatures of RCB stars.
Evans, A.; Bode, M. F.; Albinson, J. S. +1 more
IUE observations and optical-IR photometry are reported for a number of R Coronae Borealis stars, including the LMC object W Men. Non-line-blanketed, hydrogen-deficient model atmospheres are normalized to the data in the IR to determine effective and color temperatures. By comparing stellar flux distributions with model atmosphere calculations, wa…
The ultraviolet and optical spectrum and evolutionary status of HD 62910 (WN 6-C 4).
Willis, A. J.; Stickland, D. J.
A detailed study is presented of the combined UV-optical spectroscopy for the WN-C composite spectrum star HD62910. A reddening of E(B-V) = 0.80 + or - 0.05 is derived along with an intrinsic UV-optical continuum energy distribution fitted by a blackbody at about 30,000 K. The composite subtypes are confirmed as WN6 and WC4. The linewidths of both…
BD +37 1160 : a probable optical counterpart of the X-ray source 1H 0521+373.
Rossi, C.; Giovannelli, F.; Kurt, V. G. +13 more
Results are reported on detailed X-ray, UV, optical, and IR observations of two stars: BD + 37 deg 1146 and BD + 37 deg 1160. These data suggest that the star BD 37 deg 1160 is the optical counterpart of the X-ray source 1H 0516 + 373. It is shown that the optical spectrum of this star displays rapidly variable emision features, an IR excess emiss…
The Dynamical Mass of S MUSCAE
Cottrell, P. L.; Wallerstein, George; Bohm-Vitense, Erika +1 more
The amplitudes and phase relations of pulsational velocities of the Cepheid S Muscae, measured for lines originating at different atmospheric depths, are investigated. A mass M(A) = 4.4 + or - 0.5 solar masses is found for the Cepheid; however, the Cepheid is the evolved star and should have a mass larger than that of its companion. If the measure…
A study of ultraviolet spectra of zeta Aurigae/VV Cephei systems. XII. The physical state of supergiant chromospheres at the transition from coronae to cool winds.
Schroeder, K. -P.
Results are reported from an analysis of 20 IUE spectra of the Zeta Aur binaries HR 6902, HR 2554, and Tau Per during their near-eclipse phases in 1987-1988. The data are presented in tables and graphs and characterized in detail, with comparison of similar results for 22 Vul. It is shown (1) that the Fe II column densities at low heights (about 1…
EXOSAT Observations of Cygnus X-2 Continuum and Line Spectrum
Maraschi, L.; Tanzi, E. G.; Chiappetti, L. +7 more
An analysis of five Exosat observations of Cyg X-2, taken around a full binary orbit is presented. The data were obtained using all instrumentation (1000 lines/mm Transmission Grating Spectrometer, Channel Multiplier Array + filters, Medium-Energy experiment, and Gas Scintillation Proportional Counter) simultaneously, and span the full energy rang…
X-Ray and Ultraviolet Observations of the Seyfert Galaxy MCG 8-11-11
Maraschi, L.; Tanzi, E. G.; Chiappetti, L. +4 more
MCG 8-11-11 was observed in the 0.5-8 keV band with the EXOSAT observatory at 9 epochs in 1983-1986. Quasi-simultaneous UV observations were obtained in all but one case. The X-ray spectra are well fitted by absorbed power laws (N_H_ ~ 1.5 x 10^21^ cm^-2^, α_ph_ ~ 1.7). Small variations of the spectral shape are found with softening of the source …