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Characteristics of the Cen X-3 neutron star from correlated spin-up and X-ray tics luminosity measurements .
van der Klis, M.; Robba, N. R.; Bonnet-Bidaud, J. M.
Results are presented of one month of observations with the ESA COS-B satellite of the X-ray pulsation period of Cen X-3, together with X-ray luminosity measurements during this same time.
The data are shown to be compatible with an unbraked spin-up by accretion from a Keplerian disk onto a neutron star with f = 4µ2/730<…Ultraviolet spectrum synthesis of the helium white dwarf Ross 640.
Cottrell, P. L.; Greenstein, J. L.
The UV spectrum of the He-rich white dwarf Ross 640 was used to derive Mg, Si, and Fe abundances by a spectrum synthesis technique. The values obtained were: Mg/He = 6.8 x 10 to the -8th; Si/He = 3.2 x 10 to the -8th; Ca/He = 7.6 x 10 to the -10th; and Fe/He = 2.0 x 10 to the -9th. The abundances indicate the operation of diffusion processes withi…
Ultraviolet spectroscopic observations of VV Cep.
Dupree, A. K.; Holm, A. V.; Black, J. H. +1 more
Observations with the International Ultraviolet Explorer satellite (IUE) of the recent egress of the eclipsing binary VV Cep(M2Iabep + B) are presented. Egress in the ultraviolet lagged behind the visible egress by 2 to 3 months, as a result of higher opacity of the M star atmosphere in the ultraviolet. Shortly after visible egress, the low-disper…
The observations of the X-ray source HZ Her/Her X-1.
Davis, R. J.; Howarth, I. D.; Hammerschlag-Hensberge, G. +15 more
The results of a campaign of monitoring HZ Her with the IUE satellite are presented. The spectrum and light variation outside of eclipse are consistent with the Milgrom and Salpeter model for emission from the X-ray heated photosphere of the primary. Near eclipse there is UV flux in excess of the prediction of the heated photosphere model, which s…
Copernicus observations of neutral helium lines in early-type stars.
Dufton, P. L.; McKeith, C. D.
Observations of stellar ultraviolet He I lines at 2829, 2945, and 3187 A obtained with the Copernicus Satellite, are compared with LTE and non-LTE calculations. The stars observed cover the range of spectral types O8-B7 and luminosity Classes I-V and were chosen to have relatively low projected rotational velocities. The equivalent widths measured…
The detection of a companion star to the Cepheid variable eta Aql.
Doschek, G. A.; Mariska, J. T.; Feldman, U.
Ultraviolet spectra have been obtained with IUE of the classical Cepheid Eta Aquilae at several phases in the 7.18 day period. Significant ultraviolet emission is detected at wavelengths less than 1600 A, where little flux is expected from classical Cepheids. Furthermore, the emission at wavelengths less than about 1600 A does not vary with phase.…
Ultraviolet studies of the Magellanic Clouds-I. Interstellar lines inthe spectra of FD 70 and SK -71 45.
Nandy, K.; Willis, A. J.; Gondhalekar, P. M. +1 more
High dispersion ultraviolet spectra of the two LMC members, HD 38282 (FD 70) and HD 269676 (SK-71-45), have been obtained with IUE. Velocity profiles have been presented of the numerous interstellar lines observed in the spectra of these stars and associated with the absorption in both the Galaxy and the LMC. In both lines-of-sight well defined in…
IUE observations of the peculiar M giant HD 4174.
Sahade, J.; Stencel, R. E.
Ultraviolet spectra of the peculiar M giant HD 4174, which may possess a significant magnetic field, are shown to exhibit numerous high-excitation emission lines and no background continuum. Ionization equilibrium temperatures for species observed range from 6000 K (Mg II) up to 200,000 K (N v). Density diagnostics using line ratios indicate elect…
The recent outburst of the dwarf nova WZ Sge.
Rafanelli, P.; Ortolani, S.; Vittone, A. +1 more
Spectroscopic observations of the 1978 outburst of the singular cataclysmic variable WZ Sagittae are reported. Spectra taken near maximum and during the decline reveal weak emission lines of H alpha, H beta, He II 4686, and N II 4640 and absorption lines of hydrogen, He I and possible N II over a strong continuum well extended in the violet. UV sp…
The abundance of carbon and magnesium in the Orion Nebula
Patriarchi, P.; Perinotto, M.
The Orion nebula has been observed in two positions with IUE (International Ultraviolet Explorer) in the low-resolution mode (about 7 A) and in the spectral range 1150-3200 A. Emission lines of C II, C III, O II, and He I have been measured and used to determine what is probably the first reliable abundance of carbon in H II regions. The logarithm…