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Tank selection for Light Duty Utility Arm (LDUA) system hot testing in a single shell tank
The purpose of this report is to recommend a single shell tank in which to hot test the Light Duty Utility Arm (LDUA) for the Tank Waste Remediation System (TWRS) in Fiscal Year 1996. The LDUA is designed to utilize a 12 inch riser. During hot testing, the LDUA will deploy two end effectors (a High Resolution Stereoscopic Video Camera System and a Still/Stereo Photography System mounted on the end of the arm`s tool interface plate). In addition, three other systems (an Overview Video System, an Overview Stereo Video System, and a Topographic Mapping System) will be independently deployed and tested through 4 inch risers
A Detailed Analysis of a Cygnus Loop Shock-Cloud Interaction
The XA region of the Cygnus Loop is a complex zone of radiative and
nonradiative shocks interacting with interstellar clouds. We combine five far
ultraviolet spectral observations from the Hopkins Ultraviolet Telescope (HUT),
a grid of 24 IUE spectra and a high-resolution longslit Halpha spectrum to
study the spatial emission line variations across the region. These spectral
data are placed in context using ground-based, optical emission line images of
the region and a far-UV image obtained by the Ultraviolet Imaging Telescope
(UIT). The presence of high-ionization ions (OVI, NV, CIV) indicates a shock
velocity near 170 km/s while other diagnostics indicate v_shock=140 km/s. It is
likely that a large range of shock velocities may exist at a spatial scale
smaller than we are able to resolve. By comparing CIV 1550, CIII 977 and CIII]
1909, we explore resonance scattering across the region. We find that a
significant column depth is present at all positions, including those not near
bright optical/UV filaments. Analysis of the OVI doublet ratio suggests an
average optical depth of about unity in that ion while flux measurements of
[SiVIII] 1443 suggest a hot component in the region at just below 10^6K. Given
the brightness of the OVI emission and the age of the interaction, we rule out
the mixing layer interpretation of the UV emission. Furthermore, we formulate a
picture of the XA region as the encounter of the blast wave with a finger of
dense gas protruding inward from the pre-SN cavity.Comment: 21 pages, 9 figures, accepted by the Astronomical Journal, July 2001
Full resolution figures available at http://fuse.pha.jhu.edu/~danforth/xa
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