Search Publications
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…
Resolved Structure in the Nuclear Region of the Ultraluminous Infrared Galaxy Markarian 273
Knapen, J. H.; Laine, S.; Doyon, R. +4 more
We have studied the core morphology of the ultraluminous infrared galaxy Mrk 273 by combining a high-resolution adaptive optics near-infrared image with an optical image from the Hubble Space Telescope and interferometric radio continuum data, all at spatial resolutions of 150 mas or better. The near-infrared image reveals that the nucleus has two…
A comparative study of cosmic ray radial and latitudinal gradients in the inner and outer heliosphere
Kunow, H.; Wibberenz, G.; Heber, B. +6 more
The radial and latitudinal intensity gradients of 145-255 MeV/nucleon He, 34-50 MeV/nucleon He and 30-69 MeV H are studied over an extensive range of heliocentric distances and latitudes for the 1993.0-1996.0 time period using data from cosmic ray experiments on the Ulysses, IMP 8, Voyager 1 and 2, and Pioneer 10 spacecraft. The radial gradients a…
Observations of the Hubble Deep Field with the Infrared Space Observatory - IV. Association of sources with Hubble Deep Field galaxies
Elbaz, D.; Danese, L.; Franceschini, A. +17 more
We discuss the identification of sources detected by the Infrared Space Observatory (ISO) at 6.7 and 15 µ in the Hubble Deep Field (HDF) region. We conservatively associate ISO sources with objects in existing optical and near-infrared HDF catalogues using the likelihood ratio method, confirming these results (and, in one case, clarifying th…
Ultraviolet Coronagraph Spectrometer Observation of the 1996 December 23 Coronal Mass Ejection
Romoli, M.; Raymond, J. C.; Ciaravella, A. +9 more
The Ultraviolet Coronagraph Spectrometer (UVCS) aboard the Solar and Heliospheric Observatory (SOHO) observed a spectacular coronal mass ejection (CME) caused by a prominence eruption on 1996 December 23. The evolution of the ejected prominence material was followed for 1 hr and 50 minutes. The observation consists of a series of 5 minute exposure…
Deep HST/FOC Imaging of the Central Density Cusp of the Globular Cluster M15
King, Ivan R.; Sosin, Craig
Using the Faint Object Camera on the repaired Hubble Space Telescope, we have observed two fields in the globular cluster M15:\ the central density cusp, and a field at r = 20''. These are the highest-resolution images ever taken of this cluster's dense core, and are the first to probe the distribution of stars well below the main-sequence turnoff…