Search Publications
Missions
Journals
Publication Years
Improved Parameters and New Lensed Features for Q0957+561 from WFPC2 Imaging
Tyson, J. Anthony; Fischer, Philippe; Bernstein, Gary +1 more
New Hubble Space Telescope WFPC2 observations of the lensed double QSO 0957+561 will allow stronger constraints on the lens mass distribution and hence will refine the derived value of H0. We first present improved optical positions and photometry for the known components of this lens. The optical separation between the A and B quasar i…
Tri-Phonic Helioseismology: Comparison of Solar P Modes Observed by the Helioseismology Instruments Aboard SOHO
Henney, C. J.; Hoeksema, J. T.; Baudin, F. +17 more
The three helioseismology instruments aboard SOHO observe solar p modes in velocity (GOLF and MDI) and in intensity (VIRGO and MDI). Time series of two months duration are compared and confirm that the instruments indeed observe the same Sun to a high degree of precision. Power spectra of 108 days are compared showing systematic differences betwee…
MHD Interpretation of LASCO Observations of a Coronal Mass Ejection as a Disconnected Magnetic Structure
Llebaria, A.; Michels, D. J.; Koomen, M. J. +15 more
We present a qualitative and quantitative comparison of a single coronal mass ejection (CME) as observed by LASCO (July 28-29, 1996) with the results of a three-dimensional axisymmetric time-dependent magnetohydrodynamic model of a flux rope interacting with a helmet streamer. The particular CME considered was selected based on the appearance of a…
Extension of coronal structure into interplanetary space
Habbal, Shadia Rifai; Woo, Richard
We investigate the extension and evolution of the solar corona into interplanetary space by comparing 1995 Ulysses radio occultation measurements of path-integrated electron density and density fluctuations measured between 21 and 32 Ro, with simultaneous white-light measurements made by the HAO Mauna Loa K-coronameter below 2.5 Ro…
A Linear Relationship between the Latitude Gradient and 26 Day Recurrent Variation in the Fluxes of Galactic Cosmic Rays and Anomalous Nuclear Components. I. Observations
Zhang, Ming
We find that there exists a linear relationship between the magnitude of latitude gradient and the amplitude of 26 day recurrent variations in the fluxes of galactic cosmic rays and anomalous nuclear components. This result is based on energetic charged particle measurements from the University of Chicago High Energy Telescope (HET) in the Cosmic …
Interpretation of Ultraviolet Absorption Lines in SN 1006
Crenshaw, D. M.; Sarazin, C. L.; Wu, C. -C. +2 more
We present a theoretical interpretation of the broad silicon and iron ultraviolet absorption features observed with the Hubble Space Telescope (HST) in the spectrum of the Schweizer-Middleditch star behind the remnant of SN 1006. These features are caused by supernova ejecta in SN 1006.
We propose that the redshifted Si II 1260 Å feature cons…EUV Observations of a Macrospicule: Evidence for Solar Wind Acceleration?
Harrison, R. A.; Pike, C. D.
We present a unique observation of a macrospicule, recorded in extreme ultraviolet light on 11 April 1996, using the Coronal Diagnostic Spectrometer (CDS) on board the Solar and Heliospheric Observatory (SOHO). The observation was made by chance as part of a daily, large-area mapping sequence. Although the feature has some characteristics of the c…
Eclipse Mapping of the Accretion Disk Wind in the Cataclysmic Variable UX Ursae Majoris
Drew, Janet E.; Knigge, Christian
We present the results of an effort to model recent HST eclipse observations of the C IV 1550 Å resonance line in the high-inclination nova-like cataclysmic variable UX UMa. Assuming this line to be predominantly wind-formed, we are able to roughly reproduce the shapes and strengths of the observed line profiles (both away from and during eclipse)…
An adaptive grid code for high resolution 1-D hydrodynamics of the solar and stellar transition region and corona
Peres, G.; Reale, F.; Betta, R. +1 more
We present a new version of the Palermo-Harvard hydrodynamic model of plasma confined in coronal loops, based on a regridding algorithm which ensures limited variations of thermodynamical variables across grid points. The code provides an accurate description of the dynamics of the chromosphere-corona transition region, in spite of the very steep …
Additional Observations and Analysis of the Lyman-α Absorption Lines toward the QSO Pair Q0107-025A,B
Morris, Simon L.; Weymann, Ray J.; Foltz, Craig B. +3 more
We present further analysis and discussion of the properties of the absorption lines in the QSO pair Q0107-025A,B (zem = 0.956, 0.952; angular separation 1.29 arcmin) based upon spectroscopy obtained with the Faint Object Spectrograph (FOS) of the Hubble Space Telescope (HST). We also present observations of the pair at shorter waveleng…