Search Publications
Missions
Journals
Publication Years
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 …
Properties and Nature of Be Stars. 14. Is KX And a Strongly Interacting Binary?
Harmanec, P.; Hadrava, P.; Koubsky, P. +5 more
This paper summarizes and adds to the observational knowledge of KX And, a peculiar emission-line object. A formal orbital solution, based on new Ondrejov and all previously published radial velocities of the metallic shell lines in the optical region has led to an improved ephemeris. Radial velocities of various lines measured in the IUE spectra …
EXOSAT measurements of the pulse period of VELA X-1.
Raubenheimer, B. C.; Oegelman, H.
Seven new pulse period determinations of Vela X-1 have been made using the existing Exosat data. The measurements span one year and partly fill in the 3.2 yr gap between Tenma and Ginga measurements. The new results show that one pulse period of Vela X-1 continued with an epoch or near-constant period starting in 1981 and lasting up to at least Ma…
An Evolving Relativistic Jet Model for the BL Lacertae Object Markarian 421
Kondo, Y.; Urry, C. M.; Hutter, D. J. +2 more
Coordinated observations of the nearby BL Lacertae object Mrk 421 obtained during 1980 May, 1984 January, and 1984 March are described. These observations give a time-frozen picture of the continuous spectrum of Mrk 421 at X-ray, ultraviolet, optical and radio wavelengths. The observed spectra have been fitted to an inhomogeneous relativistic jet …
First observations of a corona of a cool bright giant with height resolution.
Reimers, D.; Baade, R.; Schroeder, K. -P. +1 more
Two time series of observations of the corona of HR 6902, as seen in the CIV and SiIV absorption lines during the 1988 and 1989 eclipses, are used to examine the density distribution of the expanding corona as a function of height. It is shown that the scaling laws for thermally driven winds predict coronal densities and mass-loss rates too low by…