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X-ray spectrum of the 2A 0335+096 cluster of galaxies.
Singh, K. P.; Westergaard, N. J.; Schnopper, H. W.
The paper presents the X-ray spectrum of a poor cluster of galaxies 2A 0335 + 096 obtained with the medium energy and the gas scintillation proportional counter experiments on board Exosat. The observed spectrum is best explained by a thermal bremsstrahlung emission process from a hot intracluster gas with a temperature of about 3.4 x 10 to the 7t…
EXOSAT observations of GX 304-1 in an X-ray of state.
Pietsch, W.; Kahabka, P.; Gottwald, M. +2 more
Three EXOSAT observations of the Be/neutron star X-ray binary system GX 304-1 in July/August 1984 around the time of an expected periodic outburst occurring at 132.5 d intervals showed no detectable flux of X-rays. The derived upper limits of the flux in the low and medium energy range (0.03 - 2.4 keV and 2 - 6 keV) are both 3×10-12erg …
The Cepheid Mass Problem and Cepheid Binaries
Bohm-Vitense, E.
Existing mass determinations for Cepheids with different periods are examined. Wesselink masses are independent of the adopted distance scale. For short periods (less than 6 days) they follow the sequence of evolutionary masses. For periods longer than 10 days they are lower by up to a factor of 2. The lower mass branch joins up with the bump mass…
A study of UV spectra of zeta Aur/VV CEP stars. IX. Mass-loss and wind properties of the solar type supergiant 22 VUL (G3Ib-II).
Reimers, D.; Che-Bohnenstengel, A.
Phase-covering, high resolution IUE spectra of wind lines of the Zeta Aurigae type eclipsing binary 22 Vul (G3 Ib-Il + B9) have been analysed in terms of mass4oss and wind properties. We find a wind velocity of v∞ = 160 ± 20KM s-1 and a mass-loss rate of M = 6 1O-9 Msun yr-1 for the G supergiant primary.…
NE III charge-exchange lines in the planetary nebula NGC 3918.
Harrington, J. P.; Clegg, R. E. S.; Storey, P. J.
The detection of Ne III triplet and quintet lines near 2600 Å in the planetary nebula NGC 3918 is reported. They are excited mainly by charge-transfer reactions between Ne3+ and H0. Empirical reaction rates for triplet and quintet exit channels, deduced from a photoionization model of the nebula and the line strengths, are wi…
The ultraviolet variability of the symbiotic star HBV 475. II. Study of line flux variations.
Schmutz, W.; Nussbaumer, H.; Mueller, B. E. A.
The symbiotic star HBV 475 (= V1329 Cyg) is one of the few symbiotics where periodic variations in the ultraviolet line fluxes have been observed. The authors collect the IUE observations between June 1979 and December 1984. Extending the work of Nussbaumer and Schmutz (1983), who presented a detailed study of this object, the authors establish th…
X-ray and optical variability in the low-mass burst source X 1735-444.
Charles, P. A.; Corbet, R. H. D.; Smale, A. P. +2 more
The low-mass X-ray burst source X1735 - 444 was observed with Exosat for 9 hr on August 23, 1984. The source exhibited a high level of persistent X-ray emission throughout the observation, with variations of about 20 percent and one burst. In contrast to previous observations of this source, the softness of the X-ray emission was found to be corre…
Ultraviolet, Optical, Infrared, and Microwave Observations of HR 5110
Linsky, J. L.; Simon, Theodore; Ayres, T. R. +5 more
HR 5110 is a close binary system (P = 2d.6) with the characteristics of an Algol system. Because the primary star is relatively cool (F2 IV) and there is no apparent emission from an accretion disk, the authors were able to detect in IUE spectra the emission of an active chromosphere and transition region of the cooler (K0 IV) secondary…
The ultraviolet spectrum of upsilon Sagittarii.
Hack, M.; Parthasarathy, M.; Cornachin, M.
IUE high resolution spectra of Upsilon Sgr are analyzed. The interstellar lines of metal and ionized elements and the phase-dependent variations of the stellar and circumstellar lines are studied. The characteristics (absorption strength and terminal velocities) of stellar wind features at all the orbital phases are described. The data reveal that…
Multilevel line formation in the expanding envelope of zeta Aur/VV CEP systems.
Baade, R.
The Sobolev method is the basis of the present multilevel formalism for UV line profiles in Zeta Aur systems; atomic models for Si II and Fe II UV multiplet 9 and 191 are used to study problems implicated in the two-level approximation. The first Si II model encompasses 11 composite levels together with two continua, and all possible interlocking …