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Microwave Observation of Eruptive Solar Events with and without Flare Activity
Shibasaki, K.; Hori, K.; Koshiishi, H. +2 more
We present microwave (17 GHz) observations of eruptive activity in four solar coronal events with the Nobeyama Radioheliograph. These are weak events occurring at or near the solar limb associated with several types of activity: polar crown activity, prominence eruptions, and arcade flares. The morphological evolutions of the microwave sources in …
Temporal Variations of the White Dwarf and Disk in OY Carinae Following the 1992 Superoutburst
Horne, Keith; Marsh, T. R.; Sion, E. M. +2 more
Hubble Space Telescope observations of the eclipsing dwarf nova OY Carinae after its 1992 April superoutburst are used to isolate ultraviolet spectra (1150-2500 Å at 9.2 Å FWHM resolution) of the white dwarf, the accretion disk, and the bright spot. The white dwarf spectra have a Stark-broadened photospheric Lyα absorption feature but are veiled b…
An Estimation of the Shape and Location of the Heliospheric Termination Shock
Moussas, X.; Exarhos, G.
We calculate semianalytically the distance to the heliospheric termination shock, and we use Ulysses measurements as data input for a realistic application. Therefore, we can find directly the consequences of the solar wind latitudinal variation on the shape of the termination shock. The model that we use is an approximate gasdynamic model. Our pu…
Two-dimensional Modeling of the Solar Oscillation l-ν Power Spectrum
Jefferies, Stuart M.; Meunier, Nadège
We describe an algorithm which can accurately model the spatial-temporal l-ν solar oscillation power spectrum over large ranges in frequency (ν) and degree (l). We show how modeling in two dimensions provides a better representation of the observed spectrum than can be obtained with traditional one-dimensional approaches. The gain comes from using…
The IUE and Hubble Space Telescope GHRS Spectrum of the ``Hybrid''/PG 1159-Type Central Star of the Planetary Nebula NGC 7094
Feibelman, Walter A.
Absorption features in the IUE spectrum of the ``hybrid'' PG 1159-type central star of NGC 7094 have been identified and measured. We report equivalent widths for photospheric Fe VI and Fe VII features, interstellar and circumstellar absorptions, and variability of O V λ1371 and C IV λ1549 P Cygni profiles. The terminal wind velocity of -3680+/-30…
Interpreting the Mg IIh andk Line Profiles of Mira Variables
Wood, B. E.; Karovska, M.
We use radiative transfer calculations to reproduce the basic appearance of Mg II lines observed from Mira variables. These lines have centroids that are blueshifted by at least 30 km s-1 from the stellar rest frame. It is unlikely that flow velocities in the stellar atmospheres are this fast, so radiative transfer effects must be respo…
Low-Energy Anomalous Cosmic Rays in the Ecliptic Plane: 1-5 AU
Lanzerotti, L. J.; Maclennan, C. G.
Anomalous cosmic-ray (ACR) oxygen (O) fluxes in the energy range 0.5-5.0 MeV nucleon-1 were measured in the ecliptic plane at 1 and 5 AU in 1997 and 1998. Using measurements from essentially identical instruments on the Advanced Composition Explorer (ACE) and Ulysses spacecraft, we were able to monitor the decrease with time of the ACR …
Ultraviolet Emission Lines in BA and Non-BA Giants
Robinson, Richard D.; Carpenter, Kenneth G.; Böhm-Vitense, Erika
With the Hubble Space Telescope (HST) and the Goddard High Resolution Spectrograph we have observed four barium and three weak barium stars in the ultraviolet spectral region, together with two nonpeculiar giant standard stars. An additional suspected Ba star was observed with HST and the Space Telescope Imaging Spectrograph. In the H-R diagram, t…