Search Publications
The discovery of low-level iron K line emission from CYG X-1.
White, N. E.; Barr, P.; Page, C. G.
The results of seven observations of the X-ray spectrum of Cyg X-1, made using the gas scintillation proportional counter on board the Exosat Observatory are presented. The discovery of a broad emission feature at 6.2 keV is reported with an equivalent width of typically 120 eV. The line is resolved to have an FWHM of about 1.2 keV. There is no ev…
Stellar winds from hot stars in the Magellanic clouds.
Conti, P. S.; Garmany, C. D.
O and B stars in the LMC and SMC have been observed with the IUE in order to compare their winds and mass loss rates with those of their galactic counterparts. It is found that while the wind terminal velocities are generally about 20 percent lower than in galactic stars of the same spectral type, it is not clear that the mass loss rates are signi…
The massive wind of S Dor.
Waters, L. B. F. M.; Stahl, O.; Leitherer, C. +4 more
Photometric and spectroscopic observations and UV spectrograms of the variable star S Dor are presented. The equipment used to obtain these data are described. The pseudophotosphere indicated by the absorption lines is examined; pulsation-like motions in the pseudophotosphere are detected. The UV data, which are characterized by Fe II and ionized …
An X-ray, optical and radio study of PKS 0745-191 : a massive coolingflow.
McHardy, I.; Fabian, A. C.; Elvis, M. +7 more
The X-ray source 3A 0745-191 is identified with intracluster gas surrounding the giant galaxy containing the radio source, PKS 0745-191, which lies at z = 0.1. The gas is cooling at the unprecedented rate of 1000 M_sun;yr-1. Optical line-emitting gas extends more than 10 kpc from the centre of the galaxy and corroborates the high mass-f…
An extended X-ray low state from Hercules X-1
Pietsch, W.; Parmar, A. N.; White, N. E. +4 more
Hercules X-1 exhibits a 35-day cycle in its X-ray intensity1,2 in addition to its pulsar rotational and orbital periodicities of 1.24 s and 1.7 days respectively. The effects of X-ray heating on the companion are visible throughout the 35-day cycle3, suggesting that the observed intensity modulation is caused by periodic bloc…
The optical spectrum of hydrogen at 160-350 million gauss in the white dwarf GRW +70 8247.
Liebert, J.; Stockman, H. S.; Angel, J. R. P.
Spectra from the magnetic white dwarf Grw +70 deg 8247 are compared with Roesner et al's. (1984) hydrogen spectrum up to 10 to the 9th G. It is noted that nearly all definite absorption features coincide with transitions whose energy is stationary or nearly stationary, with field strength in the 1.6 to 3.5 X 10 to the 8th G range. The complex spec…
Stellar activity in synchronized binaries. I. Dependence on rotation.
Walter, F. M.; Basri, G.; Laurent, R.
The authors have examined a large sample of late-type binaries with orbital periods from 1 to 100 days for relationships between stellar activity and rotation period, which is assumed to be synchronized with the stellar orbital period. Most of the systems are in the RS Canum Venaticorum class of close binaries. The activity diagnostics were observ…
The ejection of shells in the stellar wind of the hypergiant P Cygni (B1Ia+).
Lamers, H. J. G. L. M.; Cassatella, A.; Korevaar, P.
Radial velocity variations of six Fe II and six Fe III lines in the UV spectrum of the hypergiant star P Cygni (HD 193237) are studied in 33 high resolution IUE spectra, obtained over an interval of more than 5 yr. The Fe II lines have a stable component at -206±2 km s-1 which did not vary in velocity nor in strength in 5 yr. There are …
A study of ultraviolet spectra of zeta Aurigae/VV Cephei systems. VII. Chromospheric density distribution and wind acceleration region.
Schroeder, K. -P.
Chromospheric eclipse spectra have been obtained for three Zeta Aurigae binary systems using the International Ultraviolet Explorer (IUE) spacecraft. In order to fit average density models to the chromospheres, 3 samples of column densities (for 31 Cygni, 32 Cygni, and Zeta Aurigae K giants) were used. Wind velocities were derived assuming a conti…
The ultraviolet spectra of intermediate-redshift quasars.
Huggins, P. J.; Kinney, A. L.; Bregman, J. N. +1 more
In the present sample of 21 intermediate redshift quasars, for which IUE Lyman-alpha line flux and UV continuum observations have been conducted, an extrapolation of the continuum to the X-ray region is noted to fall at least 2-sigma above the measured X-ray flux, at 2 keV, for two-thirds of the sample. The strength of Lyman-alpha is well correlat…