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X-Ray, Optical, and Infrared Luminosity Correlations in Radio-quiet Quasars
Kriss, Gerard A.
For a sample of 88 radio-quiet quasars that includes 15 X-ray upper limits, I find that the X-ray and IR luminosities follow a significantly nonlinear relation (L_2keV_ ~ L^0.73^_1 micron_) that is consistent with that found for the X-ray and optical luminosities. The redshift dependence is weak and may be nonexistent. The shape of the optical thr…
Very extended ionized gas in radio galaxies - IV. PKS 2152-69.
Snijders, M. A. J.; di Serego Alighieri, S.; Fosbury, R. A. E. +5 more
Optical, radio and ultraviolet observations of the luminous southern radio elliptical galaxy PKS 2152-69 are presented. Narrow-band images and long-slit spectra reveal a system of low-ionization filaments extending out to a maximum radius of 20 arcsec (16kpc; H_0_=50 km s^-1_ Mpc^-1^ as used throughout this paper). To the north-east, however, a lu…
An Ultraviolet Spectral Atlas of Interstellar Lines toward SN 1987A
Panagia, N.; Grewing, M.; Wamsteker, W. +3 more
We present a spectral atlas of the interstellar spectrum toward SN 1987A in the Large Magellanic Cloud. The data used in constructing the atlas were obtained with the IUE satellite as part of the ESA Target of Opportunity Program for observing bright supernovae and were collected within the first few days following discovery of SN 1987A. At that t…
The chemical composition of the lambda Bootis stars.
Baschek, B.; Slettebak, A.
Measurements of the equivalent widhts of 24 UV lines from IUE spectra of 10 λ Bootis or suspected λ Bootis stars and 19 normal standard stars of spectral types B8-A7 are compared with line strengths calculated from model atmospheres. The light elements (C, N, and O) in the λ Boo stars are in the range slightly overabundant relative to the standard…
EXOSAT Observations of the Cassiopeia A Supernova Remnant
White, N. E.; Jansen, F.; Smith, A. +3 more
The young supernova remnant Cas A has been observed with the European X-ray observatory satellite Exosat. The remnant was observed with all instruments covering the range from 0.5 to 25 KeV. It is shown here that the emission from the remnant cannot be described by a two-temperature isothermal plasma in collisional ionization equilibrium. A simple…
The ionopause transition and boundary layers at comet Halley from Giotto magnetic field observations
Neubauer, F. M.
Giotto magnetic field observations at a time resolution of 28.24 vectors per second in the innermost part of the interaction region of comet Halley with the solar wind have yielded the following results: (1) The outer boundary of the cavity, the ionopause, has a thickness of 25 km only, both inbound and outbound, and magnetic field magnitude drops…
Contemporaneous X-Ray and VLBI Radio Observations of the Quasar NRAO 140
Marscher, Alan P.
The quasar NRAO 140 was observed at various times between 1978 and 1985 at X-ray energies using HEAO I, the Einstein Observatory, and EXOSAT. The author also observed this source a number of times with multifrequency VLBI between 1980 and 1984. In this paper, the author combines new observations with those previously published to present a time hi…
Redshifts of High Temperature Emission Lines in the Far-Ultraviolet Spectra of Late-Type Stars. II. New, Precise Measurements of Dwarfs and Giants
Ayres, Thomas R.; Jensen, Eberhard; Engvold, Oddbjorn
Results are presented from an IUE SWP camera investigation of the occurrence of gasdynamic flows, analogous to the downdrafts of 10 to the 5th K material observed over magnetic active regions of the sun, among stars of late spectral type. The SWP calibration spectra study conducted documents the existence of local, small, persistent distortions of…
Co-ordinated VLA and EXOSAT observations of the flrae stars UV Ceti, EQ Pegasi, YZ Canis Minoris and AD Leonis.
Pallavicini, R.; Kundu, M. R.; White, S. M. +1 more
The authors have observed four flare stars (UV Cet, EQ Peg, YZ CMi and AD Leo) simultaneously with the VLA and the EXOSAT satellite over continuous periods of 7 - 10 h. This is the first time that flare stars were observed simultaneously in X-rays and at microwave frequencies with high sensitivity instrumentation. All stars were detected both at t…
The Ultraviolet Spectrum of Noncoronal Late-Type Stars: The Gamma Crucis (M3.4 III) Reference Spectrum
Brown, Alexander; Johansson, Sveneric; Carpenter, Kenneth G. +3 more
A guide is presented to the UV spectrum of M-type giants and supergiants whose outer atmospheres contain warm chromospheres but not coronae. The M3 giant Gamma Crucis is taken as the archetype of the cooler, oxygen-rich, noncoronal stars. Line identifications and integrated line flux measurements of the chromospheric emission features seen in the …