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HST Imaging of Hydrogen-poor Ejecta in Abell 30 and Abell 78: Wind-blown Cometary Structures
Harrington, J. P.; Borkowski, Kazimierz J.; Tsvetanov, Zlatan +1 more
HST Faint Object Camera images of hydrogen-poor gas in the planetary nebulae A30 and A78 have revealed remarkable 'cometary' structures in the O III 5007-A forbidden line. Most of these cometary structures, consisting of compact (0.15-0.5 arcsec) knots with radial tails several arcsec in length, are located in an equatorial plane in both nebulae. …
Evaluation of Emission Mechanisms at omega P E Using ULYSSES Observations of Type III Bursts
Goldstein, M. L.; Stone, R. G.; Lengyel-Frey, D. +1 more
We present the first observational tests of existing theories for the generation of type III radio bursts emitting at the fundamental plasma frequency, ωpe. This study is based on local radio emission and in situ wave phenomena associated with four interplanetary type III radio bursts observed by the unified radio and plasma wave experi…
High-Energy Spectrum of Cygnus X-1 Revisited
Done, C.; Fabian, A. C.; Matt, G. +1 more
The X-ray spectrum of Cyg X-1 is probably produced by thermal Comptonization in an accretion disk corona. Photons reflected from the disk are also Comptonized, so the predicted reflection spectrum is dependent on the optical depth and temperature of the scattering medium. Thus, observations of reflection in the 2-20 keV energy range can constrain …
Binary Star Orbits From Speckle Interferometry. V. A Combined Speckle/Spectroscopic Study of the O Star Binary 15 Monocertis
Gies, Douglas R.; Shara, Michael M.; Penny, Laura R. +7 more
We report on the discovery of a speckle binary companion to the O7 V (f) star 15 Monocerotis. A study of published radial velocities in conjunction with new measurements from Kitt Peak National Observatory (KPNO) and IUE suggests that the star is also a spectroscopic binary with a period of 25 years and a large eccentricity. Thus, 15 Mon is the fi…
New detections of Ly-alpha emission in young galaxies.
Terlevich, Roberto; Terlevich, Elena; Diaz, Angeles I. +1 more
We report IUE observations of two extremely low-metallicity H II galaxies. Ly α emission was detected in both galaxies. Our results confirm previous findings that young or unevolved galaxies exhibit weak or absent Ly α emission combined with a strong UV continuum, and that the Ly α/Hβ ratio and metal content are correlated in the sense that the lo…
The dusty ballerina skirt of Jupiter
Horanyi, M.; Gruen, E.; Morfill, G.
We suggest a model to explain the unexpected recurrent dust events that were observed during the Jupiter encounter by the dust detector on board the Ulysses spacecraft. This model is based on dust-magnetosphere interactions. Dust particles inside the Jovian magnetosphere collect electrostatic charges and their interaction with the magnetic and ele…
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…
Bernstein waves in the Io plasma torus: A novel kind of electron temperature sensor
Moncuquet, Michel; Meyer-Vernet, Nicole; Hoang, Sang
During Ulysses passage through the Io plasma torus, along a basically north-to-south trajectory crossing the magnetic equator at R~7.8 RJ from Jupiter, the Unified Radio and Plasma Wave experiment observed weakly banded emissions with well-defined minima at gyroharmonics. These noise bands are interpreted as stable electrostatic fluctua…
Interstellar MG II and C IV Absorption toward Markarian 205 by NGC 4319: an ``Optically Thick'' QSO Absorption System
Bowen, David V.; Blades, J. C.
We have used the Goddard High-Resolution Spectrograph aboard HST to detect interstellar Mg II and C IV absorption lines toward Mrk 205, a QSO whose sightline passes within 3 h^-1^ kpc of the foreground galaxy NGC 4319. Absorption is detected from both local Milky Way gas and from NGC 4319, making this the first observation of an isolated, low-reds…
Ultraviolet Line Diagnostics of Accretion Disk Winds in Cataclysmic Variables
Shlosman, Isaac; Vitello, Peter
The IUE data base is used to analyze the UV line shapes of the cataclysmic variables RW Sex, RW Tri, and V Sge. Observed lines are compared to synthetic line profiles computed using a model of rotating biconical winds from accretion disks. The wind model calculates the wind ionization structure self-consistently including photoionization from the …