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Elemental abundances for Nova V693 Coronae Austrinae 1981
Shore, Steven N.; Starrfield, Sumner; Vanlandingham, Karen M.
We present an analysis of the UV spectra of the fast ONeMg nova V693 Coronae Austrinae 1981. Observations with IUE began on 1981 April 10 and continued until 1981 November 14. We find the reddening for the nova to be E(B-V)~=0.2+/-0.1. Using the photoionization code cloudy90.02 and the minimization routine minuit, we derive elemental abundances fo…
Hubble Space Telescope Imaging of the Central 1 Kiloparsec of M81
Ford, Holland; Devereux, Nick; Jacoby, George
M81 is the closest example of a galaxy that exhibits both LINER and Seyfert 1 characteristics. New, postrepair (cycle 5), Hubble Space Telescope imaging observations of the central kpc of M81 are presented, specifically, WFPC2 Hα and continuum images, a WFPC2 UV continuum (1500 Å) image, and a V-band faint object camera (FOC) image. The continuum …
The Relationship of Green-Line Transients to White-Light Coronal Mass Ejections
Llebaria, A.; St. Cyr, O. C.; Plunkett, S. P. +18 more
We report observations by the Large Angle Spectrometric Coronagraph (LASCO) on the SOHO spacecraft of three coronal green-line transients that could be clearly associated with coronal mass ejections (CMEs) detected in Thomson-scattered white light. Two of these events, with speeds >25 km s-1, may be classified as `whip-like' transien…
Interferometric Angular Diameters of Mira Variables with the Hubble Space Telescope
Munari, Ulisse; Whitelock, Patricia A.; Feast, Michael W. +1 more
This paper presents the first successful interferometric observations of angular diameters with the astrometer Fine Guidance Sensor (FGS) aboard the Hubble Space Telescope, the only optical interferometer operating in space. We report single-epoch angular diameters in visible light for the two Mira-type variables, R Leonis and W Hydrae, along two …
Experimental constraints on pulsed and steady state models of the solar wind near the Sun
Habbal, S. R.; Wang, Y. -M.; Feldman, W. C. +1 more
Ulysses observations of the high-latitude solar wind were combined with Spartan 201 observations of the corona to investigate the nature and extent of uncertainties in our knowledge of solar wind structure near the Sun. In addition to uncertainties stemming from the propagation of errors in density profiles inferred from coronagraph observations […
Atmospheric Structure of Neptune in 1994, 1995, and 1996: HST Imaging at Multiple Wavelengths
Hammel, H. B.; Lockwood, G. W.
Hubble Space Telescope imaging of Neptune in 1994, 1995, and 1996 reveals changes in atmospheric features. Dark spots at 467 nm near latitude +31° were present in both 1994 and 1995, but absent from images in March 1996. However, a larger data set in August 1996 (Sromovskyet al., Bull. Am. Astron. Soc.28,1077, 1996) revealed a dark spot. The featu…
Solar Coronal Heating: AC versus DC
Martens, Petrus C. H.; Milano, Leonardo J.; Gómez, Daniel O.
The heating of the plasma confined in active regions of the solar corona is caused by the dissipation of magnetic stresses induced by the photospheric motions of the loop footpoints. The aim of the present paper is to analyze whether solar coronal heating is dominated by slow (DC) or rapid (AC) photospheric driving motions. We describe the dynamic…
The Narrow-Line Region of NGC 4151: A Turbulent Cauldron
Axon, David J.; Macchetto, F. D.; Capetti, A. +1 more
We present the first results of the Hubble Space Telescope/Faint Object Camera long-slit spectroscopy of the inner 8" of the narrow-line region (NLR) of NGC 4151 at a spatial resolution of 0.029". The emission gas is characterized by an underlying general orderly behavior, consistent with galactic rotation, over which are superposed kinematically …
Hubble Space Telescope Discovers Optical Emission from the Radio Pulsar PSR 1055-52
Caraveo, P. A.; Bignami, G. F.; Mignani, R.
Optical/UV emission from isolated neutron stars, if detected, represents a valuable indicator of the pulsar's emission mechanisms, and more so for those objects of ``intermediate'' age, where thermal and nonthermal processes are known to coexist. PSR 1055-52 is a middle-aged pulsar and a strong γ-ray emitter. As such, it represents a logical targe…
The northern edge of the band of solar wind variability: Ulysses at ∼4.5 AU
McComas, D. J.; Goldstein, B. E.; Bame, S. J. +4 more
Ulysses observations reveal that the northern edge of the low-latitude band of solar wind variability at ∼4.5 AU was located at N30° in the latter part of 1996 when solar activity was at a minimum. This edge latitude is intermediate between edge latitudes found during previous encounters with the band edge along different portions of Ulysses' pola…