NASA Scientific and Technical Aerospace Reports

egion of the supernova remnant in a spatially distinct band approximately 1deg by 4deg oriented approximately north/south.
The high-excitation C I (denoted C I*) is interpreted as evidence of a complex of shocked dense clouds inside the supernova
remnant, due to the high pressures indicated in this region. To further analyze the properties of this region of C I*, we present
new HIRES-processed IRAS data of the entire Vela SNR. A temperature map calculated from the HIRES IRAS data, based
on a two-component dust model, reveals the signature of hot dust at several locations in the SNR. The hot dust is
anti-correlated spatially with X-ray emission as revealed by ROSAT, as would be expected for a dusty medium interacting with
a shock wave. The regions of hot dust are strongly correlated with optical filaments, supporting a scenario of dense clouds
interior to the SNR that have been shocked and are now cooling behind the supernova blast wave. With few exceptions, the
lines of sight to the strong C I* pass through regions of hot dust and optical filaments. Possible mechanisms for the production
of the anomalously large columns of C I and C I* are discussed. Dense clouds on the back western hemisphere of the remnant
may explain the relatively low X-ray emission in the western portion of the Vela supernova remnant due to the slower forward
shock velocity in regions where the shock has encountered the dense clouds. An alternate explanation for the presence of
neutral, excited state, and ionized species along the same line of sight may be a magnetic precusor that heats and compresses
the gas ahead of the shock.
Author
Supernova Remnants; Excitation; Clouds; X Rays; Absorption Spectra; Detonation Waves; Shock Waves
20040050203 Lawrence Livermore National Lab., Livermore, CA
LOTIS Upper Limits and the Prompt OT from GRB 990123
Williams, G. G.; Hartmann, D. H.; Park, H. S.; Porrata, R. A.; Ables, E.; Aug. 10, 2000; 12 pp.; In English
Report No.(s): DE2004-15006145; UCRL-JC-141126; No Copyright; Avail: Department of Energy Information Bridge
GRB 990123 established the existence of prompt optical emission from gamma-ray bursts (GRBs). The Livermore
Optical Transient Imaging System (LOTIS) has been conducting a fully automated search for this kind of simultaneous low
energy emission from GRBs since October 1996. Although LOTIS has obtained simultaneous, or near simultaneous, coverage
of the error boxes obtained with BATSE, IPN, XTE, and BeppoSAX for several GRBs, image analysis resulted in only upper
limits. The unique gamma-ray properties of GRB 990123, such as very large fluence (top 0.4%) and hard spectrum, complicate
comparisons with more typical bursts. We scale and compare gamma-ray properties, and in some cases afterglow properties,
from the best LOTIS events to those of GRB 990123 in an attempt to determine whether the prompt optical emission of this
event is representative of all GRBs. Furthermore, using LOTIS upper limits in conjunction with the relativistic blast wave
model, we weakly constrain the GRB and afterglow parameters such as density of the circumburster medium and bulk Lorentz
factor of the ejecta.
NTIS
Gamma Ray Bursts; Light Emission
20040050284 Smithsonian Astrophysical Observatory, Cambridge, MA, USA
The Nature of the Vela Supernova Remnant as Revealed by O VI and C IV Absorption
Lines, Nichols J.; Slavin, J.; Anderson, C.; [2001]; 10 pp.; In English; AAS Meeting, 1999
Contract(s)/Grant(s): NAG5-8483; No Copyright; Avail: CASI; A02, Hardcopy
Highly ionized gas, in particular C IV and O VI, is produced in the interstellar medium in regions with hot (T approx.
10(exp 6) K) X-ray emitting gas and at the boundaries where hot gas and cooler (T approx. 10(exp 4) K) gas interact.
Supernova remnant shocks produce most of the hot gas in the ISM and, if they are in the correct range of speeds, should
produce observable quantities of C IV and O VI absorption. In turn, the column densities of these ions are potentially powerful
diagnostics of the shock speed and interstellar environment in which the SNR is evolving. With the advent of FUSE, the power
of this diagnostic technique is now available. We have FUSE data toward 8 stars behind the Vela SNR, and have developed
a data reduction and analysis method that produces reasonably reliable O VI column densities, in spite of the complexities of
the FUSE spectra in this region. In order to gain insight into the observational results, the Vela SNR evolution was modelled
using Piecewise Parabolic Method numerical hydrodynamics code. The code is 1-D and incorporates non-equilibrium
ionization, radiative cooling, thermal conduction and magnetic pressure.
Author
Supernova Remnants; Ionized Gases; High Temperature Gases; Absorption Spectra
20040050358 Lawrence Livermore National Lab., Livermore, CA
Using Data Mining to Find Bent-double Galaxies in the FIRST Survey
Kamath, C.; Cantu-Paz, E.; Fodor, I. K.; Tang, N.; Jun. 22, 2001; 16 pp.; In English
Report No.(s): DE2004-15006299; UCRL-JC-143458; No Copyright; Avail: Department of Energy Information Bridge
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