Search Publications
Ultraviolet and Optical Spectrophotometry of the Seyfert 1.8 Galaxy Markarian 609
Cohen, Ross D.; Ake, T. B.; Rudy, Richard J.
We present simultaneous ultraviolet and optical observations of the Seyfert 1.8 galaxy Markarian 609. The broad hydrogen lines are in the ratio Lyα/Hβ/Hα = 16/1.0/5.0. The Hβ(broad)/[O III] ratio has increased since the 1976 measurements of Osterbrock, and the Hα/Hβ ratio is no longer as large as when he classified Mrk 609 as a type 1.8 Seyfert ga…
An Exceptionally Bright, Compact Starburst Nucleus
Anderson, Scott F.; Massey, Philip; Mateo, Mario +2 more
We report observations of a remarkably bright (V ~ 13) starburst nucleus, 0833+652, which we have detected at radio, infrared, optical, ultraviolet, and X-ray wavelengths. Despite an observed flux at each of these wavelengths which is comparable to that of NGC 7714, often considered the "prototypical" example of the starburst phenomenon, 0833+652 …
The Detection of a High-Energy Break in the X-Ray Spectrum of the BL Lacertae Object PKS 0548-32
Maccagni, D.; Giommi, P.; Barr, P.
The results of a deep EXOSAT observation of the BL Lac object PKS 0548-32 performed in 1986 March are presented. The 0.05-10 keV X-ray spectrum is characterized by a relatively flat (power-law energy spectral index α ~ 0.9) continuum below 5 keV which steepens at higher energies. There is no evidence for any excess absorption intrinsic to the BL L…
An X-Ray Flare from a B9+ Post--T Tauri Star System in the Field of the Seyfert Galaxy III ZW 2
Tagliaferri, G.; Pallavicini, R.; Giommi, P. +2 more
We report the serendipitous discovery by EXOSAT of a flaring X-ray source in the field of the Seyfert type I galaxy III Zw 2. In contrast to an earlier report that attributed the variability observed by the medium energy experiment to III Zw 2, we show that the variability was entirely due to the serendipitous source. We identify this source with …
Stellar Winds in the Small Magellanic Cloud
Fitzpatrick, Edward L.; Garmany, Catharine D.
According to the predictions of line-driven stellar wind theory, the mass loss from luminous stars should be proportional to some power of the metallicity, yet previous studies have not shown this effect clearly. We have observed 22 main-sequence and giant O-type stars in the SMC with the low-resolution mode of the IUE in order to study the stella…
Fast Variations in the Ultraviolet Resonance Lines of alpha Camelopardalis (O9.5 Ia): Evidence for Blobs in the Wind
Snow, Theodore P.; Lamers, Henry J. G. L. M.; de Jager, Cornelis +1 more
The 72 IUE spectra of Alpha Cam and 19 IUE spectra of Kappa Cas, obtained during 72 hours of continuous IUE time in September 1978 were searched for variations in the profiles of the resonance lines of Si IV, C IV, and N V, and the results are discussed. The UV resonance lines in the spectra of Alpha Cam showed variations at the 2 percent level ne…
On the High-Energy Gamma-Ray Signature of Cosmic-Ray Sources
Ormes, J. F.; Ozel, M. E.; Morris, D. J.
If cosmic rays are accelerated by strong shocks, then cosmic-ray sources should be characterized by spectra, dN/dE is proportional to p^-(2.0-2.2)^, reflecting the strength of those shocks. This is expected from the "standard leaky box" model of cosmic-ray propagation in which the source spectra are harder than the observed spectra because higher …
EXOSAT and IUE Observations of SW UMa during Superoutburst
Szkody, Paula; Hassall, B. J. M.; Osborne, Julian
IUE and Exosat observations obtained during the March 1986 superoutburst of the SU UMa type dwarf nova SW UMa are presented. The observations show the presence of a hot, extensive, optically thick disk. The UV fluxes show an increase of 1000 over the quiescent values, implying a large increase in mass accretion rate. The Exosat obserations show an…
Hot Components and Circumstellar Grains in M Supergiant Syncretic Binaries
Buss, Richard H., Jr.; Snow, Theodore P., Jr.
The authors have aqcquired ultraviolet spectra and infrared data to study grains in cool star plus hot star syncretic (VV Cep) type binaries. Though M supergiants almost always have circumstellar grains, the authors found grains, from IRAS infrared photometry, in only about half of the syncretic systems. Infrared spectra revealed that the circumst…
The Abundance of Zinc in Hg-Mn Stars
Sadakane, Kozo; Takada-Hidai, Masahide; Jugaku, Jun
The resonance line of singly ionized zinc (Zn II) at 2062.00 A is quantitatively analyzed, and the abundances of Zn in atmospheres of early-type stars have been determined for the first time. The line is analyzed in IUE spectra of six reference (normal) stars between spectral types B5 and A0 and of 23 Hg-Mn stars. The abundances of Zn in the refer…