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Observation of Polar Plumes at High Solar Altitudes
Plunkett, S. P.; Andrews, M. D.; DeForest, C. E.
Using the Large-Angle Spectrometric Coronagraph (LASCO) aboard the Solar and Heliospheric Observatory (SOHO) spacecraft, we have imaged polar plumes extending 30 Rsolar from disk center in the image plane and ~45 Rsolar in three-dimensional space, a factor of 2-3 farther than previous imaging measurements and well into the co…
Late AGB Magnetic Cycles: Magnetohydrodynamic Solutions for the Hubble Space Telescope Planetary Nebula Rings
García-Segura, Guillermo; López, José Alberto; Franco, José
The Hubble Space Telescope (HST) has revealed the existence of multiple, regularly spaced, and faint concentric shells around some planetary nebulae. Here we present two- (and a half) dimensional magnetohydrodynamic numerical simulations of the effects of a solar-like magnetic cycle, with periodic polarity inversions, in the slow wind of an asympt…
Chandra X-Ray Observatory Observation of the High-Redshift Cluster MS 1054-0321
Donahue, Megan; Garmire, Gordon P.; Canizares, Claude R. +3 more
We observed MS 1054-0321, the highest redshift cluster of galaxies in the Einstein Medium Sensitivity Survey (EMSS), with the Chandra ACIS-S detector. We find the X-ray temperature of the cluster to be 10.4+1.7-1.5 keV, lower than, but statistically consistent with, the temperature inferred previously. This temperature agrees…
The Nuclear Dynamics of M32. I. Data and Stellar Kinematics
Nelson, C.; Bender, R.; Joseph, C. L. +14 more
We have obtained optical long-slit spectroscopy of the nucleus of M32 using the Space Telescope Imaging Spectrograph aboard the Hubble Space Telescope. The stellar rotation velocity and velocity dispersion, as well as the full line-of-sight velocity distribution (LOSVD), were determined as a function of position along the slit using two independen…
Properties of Solar Polar Coronal Hole Plasmas Observed above the Limb
Wilhelm, K.; Schühle, U.; Doschek, G. A. +2 more
We determine the line-of-sight emission measure distribution and nonthermal motions as a function of height above the limb in the north and south polar coronal holes. These quantities are derived from extreme-ultraviolet (EUV) spectra obtained from the Solar Ultraviolet Measurements of Emitted Radiation (SUMER) spectrometer on the Solar and Helios…
Multiwavelength Observations of the Soft Gamma Repeater SGR 1900+14 during Its 2001 April Activation
Hurley, K.; Kouveliotou, C.; Fender, R. P. +6 more
The soft gamma repeater SGR 1900+14 became active on 2001 April 18 after about 2 years of quiescence; it had remained at a very low state of activity since the fall of 1998, when it exhibited extraordinary flaring. We have observed the source in the gamma-rays and X-rays with Ulysses and Chandra and in the radio with MERLIN. We report here the con…
On the Relationship between He II λ304 Prominences and the Photospheric Magnetic Field
Wang, Y. -M.
As observed in He II λ304 images recorded at high cadence, quiescent prominences resemble long-lived systems of jets, in which chromospheric material streams continually from one footpoint area to another. To further clarify the physical nature of the source regions, we have compared He II λ304 images of on-disk prominences (filaments) with line-o…
High Spectral and Spatial Resolution Observations of Shocked Molecular Hydrogen at the Galactic Center
Yusef-Zadeh, F.; Burton, M.; Wardle, M. +2 more
The presence of OH (1720 MHz) masers and the absence of counterparts at 1665/1667 MHz has proved to be a clear diagnostic of shocked molecular gas associated with Galactic supernova remnants. This suggests that shocked molecular gas should be associated with the OH (1720 MHz) masers that have been detected in the circumnuclear disk (CND) and Sgr A…
Solar Polar Plume Lifetime and Coronal Hole Expansion: Determination from Long-Term Observations
Llebaria, A.; Lamy, P. L.; DeForest, C. E.
We have generated off-limb polar synoptic charts of polar plume evolution at various solar altitudes using EUV Imaging Telescope and Large Angle and Spectrometric Coronagraph data from 1996 December. The charts allow direct measurement of the altitude expansion of the solar minimum coronal holes. We find expansion values that are consistent with t…
On the Nature of Magnetic Shadows in the Solar Chromosphere
Judge, P. G.; McIntosh, S. W.
Recent multi-instrument spacecraft studies of the solar photosphere and chromosphere have uncovered a feature-a ``magnetic shadow''-not previously discussed in the literature. A region of the midchromosphere neighboring, but not within, a network magnetic element exhibits a suppression of both the mean UV line/continuum intensity and the character…