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The Hot White Dwarf Companions of HR 1608, HR 8210, and HD 15638
Bergeron, P.; Simon, Theodore; Landsman, Wayne
We have obtained low-dispersion IUE spectra of the late-type stars HD 15638 (F3 V), HR 1608 (=63 Eri, K0 IV), and HR 8210 (A8m). Each of these stars had been detected as a strong EUV source with the Wide Field Camera (WFC) aboard the ROSAT satellite. The short-wavelength IUE spectrum of each star reveals the presence of a hot white dwarf companion…
The Spectrum of the Planetary Nebula NGC 6567
Feibelman, Walter A.; Hyung, Siek; Aller, Lawrence H.
Because of the similarity of its spectrum to that of NGC 6572 particularly in the UV we have made a detailed study of NGC 6567 using both the IUE for the UV region and the Hamilton Echelle at Lick Observatory for the optical region. Plasma diagnostics suggest an electron temperature of about 11,500K and an electron density near 9000 cm^-3. The che…
Imaging the Bipolar Nebula around HM Sagittae
Paresce, Francesco; Hack, Warren J.
Hubble Space Telescope Faint Object Camera UV images are presented for HM Sge showing a bipolar optical nebula similar to that in R Aquarii and RX Puppis. The nebula extends to a distance of 0.174" with a P.A. of 135 degrees inside a faint halo extending to a radius of 0.28". A kinematic distance to HM Sge based on positions of features in the neb…
Signal-to-Noise Ratios in IUE Low-Dispersion Spectra. II. Photometrically-Corrected Images
Ayres, Thomas R.
The character of detector noise is explored in photometrically-corrected images from the shortwavelength and longwavelength prime intensified vidicon cameras of the International Ultraviolet Explorer. A protocol is proposed for deriving realistic "noise models"--crucial to the application of Optimal extraction algorithms like that of Kinney, Bohli…
Rapid Mass-Loss Transients in VV Cephei
Stencel, Robert E.; Potter, Daniel E.; Bauer, Wendy H.
Biweekly ultraviolet observations of the red supergiant-hot dwarf binary, VV Cephei during 1991, obtained near third quadrature, have revealed the existence of short-term continuum variations. We infer these are superposed on an underlying emission-line spectrum. The viewing geometry of this long period system suggests we are seeing a process asso…
The Companion of the Classical Cepheid Z Lacertae
Evans, Nancy R.; Welch, Douglas L.
A deep IUE exposure of the Cepheid Z Lac from 1200 to 2000 A has been taken in order to search for light from the radial velocity companion. A faint signal of approximately 1.0 X 10^-14 ergs A^-1 sec^-1 cm^-2 has been detected in the dereddened spectrum. Because this is approximately the flux expected due to "camera artifacts," we consider that at…
The Ultraviolet Spectrum of the Planetary Nebula VY 2-2
Feibelman, Walter A.
New ultraviolet short-wavelength (SWP) IUE observations for the protoplanetary nebula Vy 2-2 were obtained in the low dispersion mode. An exposure of 400 minute duration reveals a weak stellar continuum and several definite emission lines as well as a number of absorption features. Emission features of C III], Si III], and [Ne III] are clearly obs…
The Companion of the 18d Classical Cepheid YZ CAR
Evans, Nancy R.; Butler, John
We have obtained a deep IUE spectrum of the 18d Cepheid YZ Car. Flux has been detected at the level of 1-2 X 10^-15 ergs cm^-2 A^-1 sec^-1 from 1200 to 200 A, which we identify as the companion in the binary system. Since this is at least partly a result of "camera artifacts" built up during a long exposure, this is an upper limit to the flux of t…
IUE Observations of Highly Ionized Gas toward Distant Stars in the Milky Way
Sembach, Kenneth R.
Combined high-dispersion IUE spectra of interstellar Si IV, C, IV, and N V absorption along distnat lines toward early type stars in the Galactic disk and low halo are discussed. The highly ionized species have complex profiles and exhibit stronger absorption toward distant low latitude stars than toward high latitude stars. Absorption along low l…
Periodicities in the IUE Particle Radiation Data
Arquilla, Richard
The magnetospheric charged particle flux measured serendipitously by the IUE satellite during perigee passages from February 1978 to February 1989 has been searched for periodicities using Fourier transform and correlation techniques. The analysis uncovers persistent modulations of the particle flux with periods of 28 to 33 days and 15 to 17 days.…