Search Publications
IUE Observations of Z Andromedae: Spectral Variations during Quiescence and a Physical Model
Fernandez-Castro, Telmo; Cassatella, Angelo; Gimenez, Alvaro +1 more
The authors describe the results of an extensive monitoring of the ultraviolet spectrum of the symbiotic star Z And based on high- and low-resolution IUE observations made during 1978 - 1982, when the star was in a phase of quiescence. Large variations of the Balmer continuum and emission-line intensities where observed on a time scale of about 76…
4U 1626-67: The Binary with the Smallest Known Mass Function
van der Klis, M.; Verbunt, F.; Rappaport, S. +3 more
The pulsating X-ray source 4U 1626-67 is an accreting neutron star in a binary system with a very low mass companion. The authors observed the source with EXOSAT continuously for 23 hr on 1986 March 30 - 31 UT. These observations allow them to set a stringent upper limit on the projected semimajor axis of the orbit of the neutron star. The corresp…
Hard X-Ray Emission from a Type 2 Seyfert Galaxy (NGC 1068)
Elvis, Martin; Lawrence, A.
EXOSAT observations of the type 2 Seyfert galaxy NGC 1068 have detected a source in the 2-10 keV range with a flux density at 2 keV of 0.6 microJy. It has a flat (α_E_ = 0.62 +/- 0.25) power-law spectrum similar to type 1 Seyferts; Combined with Low Energy EXOSAT filter data and Einstein IPC observations, these data show that spectral curvature is…
The Reionization of Unshocked Ejecta in SN 1006
Fesen, Robert A.; Hamilton, Andrew J. S.
The validity of carbon-deflagration models white dwarf models for type Ia supernovae is investigated by examining whether most of the iron in the center of SN 1006 exists in forms other than Fe II, such as iron grains or other ionic stages of iron, as the models require. The possible ways in which iron can be hidden in SN 1006 are reviewed, and an…
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…
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…
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…
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…
EXOSAT Observations of the Supernova Remnant G109.1-1.0 and the X-Ray Pulsar 1E 2259+586
van der Klis, M.; Robba, N. R.; Smith, A. +1 more
The authors report on the EXOSAT observation of the supernova remnant (SNR) G109.1-1.0+1E 2259+586 system. The spatial distribution of the X-ray emission as derived from the low-energy (<2 keV) data is very similar to that obtained from the Einstein Observatory. The various components of the source (SNR shell, pulsar, and jet) have different sp…
Interstellar Absorption Lines in High-Resolution IUE Spectra of Cataclysmic Variables
Raymond, John C.; Mauche, Christopher W.; Cordova, France A.
High-resolution ultraviolet spectra of five cataclysmic variables obtained with the IUE are used to investigate the character of the interstellar medium in the vicinity of the sun. These spectra reveal narrow absorption features of neutral and singly ionized interstellar species, and, in SS Cyg, narrow velocity-shifted absorption features of C IV,…