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Reappearance of recurrent low-energy particle events at Ulysses/HI-SCALE in the northern heliosphere
Simnett, G. M.; Lanzerotti, L. J.; Armstrong, T. P. +4 more
In the high-latitude northern hemisphere of the heliosphere, the Heliosphere Instrument for Spectra Composition and Anisotropy at Low Energies (HI-SCALE) energetic particle detectors on Ulysses have measured quasi-recurrent ~26-day increases of 40-65 keV electrons during 11 solar rotations from October 1995 through July 1996. They do not appear on…
Abundance analysis of the slow nova PW Vulpeculae 1984
Shore, Steven N.; Hauschildt, Peter H.; Schwarz, Greg J. +1 more
We determine the elemental abundances for the ejecta of the slow nova PW Vul 1984. Our technique uses a minimization of the emission-line fits of a photoionization model to available ultraviolet, optical and infrared spectra. We find the following abundances (by number) with respect to solar: He/H=1.0+/-0.4, C/H=7.0^+7_-4, N/H=85^+59_-41 and O/H=6…
Evidence for an Anomalous State in the Black Hole Candidate 4U 1630-47
Kuulkers, Erik; van der Klis, Michiel; Parmar, Arvind N.
We have reanalyzed two EXOSAT medium-energy observations during part of the 1984 X-ray outburst of the black hole candidate transient system 4U 1630-47. One observation (May 10) shows fast-timing properties (on timescales shorter than ~250 s) typical of those of other black hole candidates in their high states. The power spectrum shows a power law…
Gamma-Ray Burst Arrival Time Localizations: Simultaneous Observations by Mars Observer, Compton Gamma Ray Observatory, and ULYSSES
Hurley, K. C.; Fishman, G. J.; Kouveliotou, C. +12 more
Between 1992 October 4 and 1993 August 1, concurrent coverage by the Compton Gamma Ray Observatory (CGRO), Mars Observer (MO), and Ulysses spacecraft was obtained for 78 gamma-ray bursts (GRBs). Although most of these were below the MO and Ulysses thresholds, nine were positively detected by all three spacecraft, with data quality adequate for qua…
Dynamic Processes in Be Star Atmospheres. VI. Simultaneous X-Ray, Ultraviolet, and Optical Variations in λ Eridani
Smith, Myron A.; Corcoran, M. F.; Murakami, T. +4 more
We document the results of simultaneous wavelength monitoring of the B2e star λ Eri. This campaign was carried out from ground stations and with the ROSAT, ASCA, IUE, and Voyager 2 space platforms during a week in 1995 February-March a smaller follow-up was conducted in 1995 September. During the first of these intervals λ Eri exhibited extraordin…
HST synthetic spectral analysis of U GEM in early and late quiescence: A heated white dwarf and accretion belt?
Horne, Keith; Sion, E. M.; Huang, M. +3 more
We have re-examined two archival HST FOS G130H spectra of the prototype dwarf nova U Geminorum obtained during its quiescence 13 days and 70 days after a wide outburst. Using synthetic spectral fitting with two flux-emitting components, a slowly rotating white dwarf photosphere, and a rapidly spinning accretion belt (Vrot sin i=3200 km …
Near Infrared Imaging of the Hubble Deep Field with the Keck Telescope
Hogg, David W.; Matthews, K.; Soifer, B. T. +4 more
Two deep K-band (2.2 microns ) images, with point-source detection limits of K=25.2 mag (one sigma), taken with the Keck Telescope in subfields of the Hubble Deep Field, are presented and analyzed. A sample of objects to K=24 mag is constructed and V606-I814 and I814-K colors are measured. By stacking visually sele…
The Nuclear Region of M51 Imaged with the HST Planetary Camera
Lauer, Tod R.; Faber, S. M.; Grillmair, Carl J. +4 more
We present high-resolution, broad- and narrow-band, pre-refurbishment images of the central region of M51 taken with the Planetary Camera of the Hubble Space Telescope. The V-band images show a rather chaotic distribution of dust lanes, though some are oriented radially, roughly aligned with the major axis of the bar, and may be transporting gas t…
Chromospheric Emission in Metal-poor Solar-Type Stars
Schrijver, Carolus J.; Peterson, Ruth C.
Cool stars like the Sun show chromospheric activity, which is largely attributed to nonradiative sources of energy linked to rotationally driven magnetic fields. However, a nonmagnetic process, such as dissipation of acoustic waves, may operate side by side with the first process. We report detections of chromospheric emission reversals in Mg II 2…
The heliospheric modulation of galactic cosmic rays at solar minimum
Potgieter, M. S.
The observations acquired by the Ulysses spacecraft since launch, but especially during the recent fast latitude scan, have provided a comprehensive, 3-dimensional view of the inner heliosphere. Together with the observations by IMP 8, Pioneer 10 and the two Voyagers, a wealth of new observations on particles and fields enables us to improve signi…