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Velocity space diffusion and nongyrotropy of pickup water group ions at comet Grigg-Skjellerup
Coates, A. J.; Neubauer, Fritz M.; Wilken, B. +1 more
The diffusion of water group cometary ions in velocity space at comet Grigg-Skjellerup was measured during the Giotto spacecraft encounter. The evolution of the collapsed pitch angle and energy distributions during the inbound and outbound passes shows that the timescale for energy diffusion may be similar to that for pitch angle diffusion. Fully …
UES and IUE observations of the O9.5V star HD 93521 : non-radial pulsatutions, wind and distance.
Howarth, Ian D.; Reid, Andy H. N.
We have obtained time-series spectroscopy of the rapidly rotating O9.5 V star HD 93521 during commissioning of the Utrecht Echelle Spectrograph (UES) on the William Herschel Telescope. The He I lines show 'wiggles' at the approximately 1% level, which move systematically from blue to red across the profile; by contrast, the He II lines do not show…
Internal structure and polarization of the optical jet of the quasar 3C273
Mackay, C. D.; Thomson, R. C.; Wright, A. E.
THE extragalactic radio source 3C273 was the first quasar to be identified1, and remains one of the nearest and most luminous quasars known. In radio images2-4, it appears as a bright, point-like nucleus from which emerges a single large jet; the jet is also apparent in optical images5-8, but the relatively poor re…
Discovery of a Magnetic/Nonmagnetic Double-degenerate Binary System
Bergeron, P.; Saffer, Rex A.; Liebert, James +1 more
We report the discovery of an unresolved binary system consisting of two degenerate stars: one a polarized object with an inferred magnetic field among the largest yet found on a white dwarf; the other a normal DA with no detectable field. We have deconvolved the composite 1250 Å-2.2 microns energy distribution into individual spectra and find tha…
Polarimetric investigatio, on interstellar dust within 50 PC from the sun.
Leroy, J. L.
We have analyzed the polarization catalogue, for 1000 stars closer than 50 Pc, which has been presented in a companion paper. Although the accuracy of the measurements is generally very good (better than 0.02% for more than 700 stars), the catalogue contains essentially unpolarized stars, which is to be related to the well known depletion of dust …
A Catalog of Stellar Lyman-Alpha Fluxes
Simon, Theodore; Landsman, Wayne
We present a catalog of stellar Ly-alpha emission fluxes, based on new and archival images obtained with the IUE spacecraft. The catalog includes 227 stars with detectable Ly-alpha emission fluxes, and upper limits on the Ly-alpha emission flux for another 48 stars. Multiple flux measurements are given for 52 stars. We present a model for correcti…
A Synoptic Study of H alpha Line Profile Variability in the T Tauri Star SU Aurigae
Giampapa, Mark S.; Basri, Gibor S.; Johns, Christopher M. +1 more
We present a catalog of 106 high spectral resolution observations of the H-alpha line profile in the T Tauri star SU Aurigae, obtained during the period from 1986 October through 1990 November. The spectra were acquired during joint synoptic programs to observe selected T Tauri stars using the Hamilton Echelle Spectrometer of the Lick Observatory …
The First Detection of Ionized Helium in the Local ISM: EUVE and IUE Spectroscopy of the Hot DA Dwarf GD 246
Bowyer, Stuart; Vennes, Stephane; Chayer, Pierre +4 more
We report observations of the extreme ultraviolet spectrum of the hot degenerate star GD 246 obtained with the EUVE. Our initial attempt at modeling the photospheric emission from the white dwarf reveals a relatively uncontaminated pure H spectrum in the range above 200 A, allowing a study of interstellar continuum absorption features in the line …
Morphology and time variation of the Jovian far UV aurora: Hubble Space Telescope observations
Paresce, Francesco; Prange, Renee; Gerard, Jean-Claude +1 more
High spatial resolution images of the north polar region of Jupiter have been obtained with the Faint Object Camera on board the Hubble Space Telescope. The first set of two images collected 87 min apart in February 1992 shows a bright (≃180 kR) emission superimposed on the background in rotation with the planet. Both Ly α images show common regio…
Cyclotron and Zeeman spectroscopy of MR Serpentis in low and high states of accretion.
Beuermann, K.; Jordan, S.; Schwope, A. D. +1 more
Phase-resolved low-resolution spectrophotometry of the polar MR Ser obtained during states of low and high accretion reveals cyclotron line emission as well as Balmer line Zeeman absorption. At both occasions the cyclotron lines move with phase. The whole system of cyclotron lines appears wavelength- and phase-shifted when the system switches from…