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The spectral signature of the cooling flow in Abell 478.
Fabian, A. C.; Edge, A. C.; Johnstone, R. M. +1 more
We present X-ray spectra of Abell 478 taken with the Ginga LAC and with the Einstein SSS. The LAC data set an upper limit of ~440 M_sun_ yr^-1^ on the mass deposition rate throughout the whole cluster if a value for the galactic absorption based on 21-cm observations of H I is adopted. The SSS data strongly require an absorbing column density well…
Radio-loud and radio-quiet quasars observed by EXOSAT.
Saxton, R. D.; Turner, M. J. L.; Stewart, G. C. +2 more
We present results from the spectral analysis of EXOSAT data on 31 quasars, 18 radio-loud and 13 radio-quiet. Simple power-law models with fixed (Galactic) absorption give acceptable fits to the spectra obtained in the 2-10 keV band. Using the results from these fits we have compared the distributions of spectral indices α for the radio-loud and r…
The EXOSAT obseravtions of SS Cygni.
Watson, M. G.; Jones, M. H.
A series of nine observations of SS Cygni made using Exosat between 1983 November and 1984 September are presented. Distinct soft amd hard X-ray emitting components were spectrally resolved by the LE and ME instruments, respectively. In quiescence the source shows hard X-ray emission with a 2-10 keV luminosity of 1.2 x 10 exp 33 (d/200 pc)-squared…
GINGA and EXOSAT observations of the Perseus cluster of galaxies.
Fabian, A. C.; Allen, S. W.; Edge, A. C. +2 more
We report observations of the Perseus cluster of galaxies made using the Ginga and EXOSAT satellites. Our results from Ginga indicate that the region around the centrally dominant galaxy NGC 1275 is well described by a model incorporating emission from an isothermal, diffuse plasma of temperature ~6.3 keV, metal abundance ~ 0.4 solar, a cooling fl…
Models for the remnants of recurrent novae - III. Comparison with the X-ray observations of RS Ophiuchi (1985).
Bode, M. F.; O'Brien, T. J.; Kahn, F. D.
The X-ray emission predicted by a model for the interaction of ejecta with a circumstellar medium is compared to Exosat observations of the 1985 outburst of the recurrent nova RS Ophiuchi. The model parameters are constrained by fitting the predicted spectrum to the first X-ray observation, made 55 days after the outburst, and are found to be cons…
The outer atmospheres of the 'hybrid' bright giants : the chromospheres of alpha TrA (K4 II), IOTA AUR (K3 II), gamma AQL (K3 II) , and theta HER (K1 II).
Harper, Graham M.
Detailed models of the chromospheres of several 'hybrid' bright giants are presented. The models extend from the base of the chromosphere and into the transition area. These chromospheric models are based on radiative transfer calculations for a range of atoms and emission lines. The presence of steep turbulent velocity gradients leads to profiles…
Time dependence of the UV resonance lines in the cataclyspic variables YZCnc, IR GEM and V 3885 Sgr.
Verbunt, F.; Collier Cameron, A.; Woods, J. A. +2 more
Orbital variations are observed in the UV resonance lines of YZ Cnc, IR Gem and V3885 Sgr. Optical spectroscopic observations of YZ Cnc show that the maximum absorption in the UV lines occurs about 0.7-0.8 orbits after the transition from red to blue of the optical emission lines. IR Gem shows orbital variations in the UV lines that are as strong …
The central star of S 216.
Tweedy, R. W.; Napiwotzki, R.
Optical and high-resolution ultraviolet spectra of LS V + 46 21, the postulated central star of the large, nearby planetary nebula S 216, have been analyzed. From modeling the line profiles, this star is found to have an effective temperature of about 90,000 K, surface gravity log g of about 7, and a He:H ratio of about 0.01. These are as expected…
H 0414+009 - an X-ray bright BL Lac with a radio tail in a distant cluster of galaxies.
Abraham, R. G.; George, I. M.; McHardy, I. M. +2 more
VLA observations of the X-ray selected BL Lac H0414+009 at 6, 20 and 90 cm show that it has a steep-spectrum (α~1; f_v_ is proportional to v^-α^) radio tail. The tail extends ~40 arcsec from the core, in a gentle curve. There is no evidence of extended emission on the opposite side of the core. This is by far the clearest example of a single-sided…
Beta Pictoris and the lambda Bootis stars : testing the accretion hypothesis.
King, Jeremy R.; Patten, Brian M.
It is suggested that Beta Pic may be an unrecognized Lambda Boo star, based on the recent discussion of its evolutionary status by Paresce and the proposal by Venn and Lambert linking circumstellar material with the Lambda Boo phenomenon. The star's metallicity, photometric indices and UV spectrum support this interpretation. If confirmed as a Lam…