SCIENTIFIC AND TECHNICAL AEROSPACE REPORTS

A Biweekly Publication of the National Aeronautics and Space Administration
VOLUME 43, ISSUE 26 - DECEMBER 30, 2005

90 ASTROPHYSICS
Includes cosmology; celestial mechanics; space plasmas; and interstellar and interplanetary gases and dust.

20050243572 Lawrence Livermore National Lab., Livermore, CA USA

Polarization Measurement of Iron L-Shell Lines on EBIT-I

Chen, H.; Beiersdorfer, P.; Robbins, D.; Smith, A. J.; Gu, M. F.; Mar. 07, 2004; 16 pp.; In English Report No.(s): DE2005-15013911; UCRL-PROC-202745; No Copyright; Avail.: National Technical Information Service (NTIS)

We report measurements of the line polarization of Ne-like and F-like of iron n=3 to n=2 transitions in the x-ray region. We used the 'two-crystal technique' developed in previous polarization measurements in our laboratory. Preliminary results from our measurements are presented together with the theoretical calculations using the Flexible Atomic Code (FAC). Our calculations show that contributions from cascades play an important role in the polarization calculations of most of the transitions. The uncertainties and difficulties of our experiments are also discussed. NTIS

Atoms; Crystals; Electron Beams; Ion Beams; Iron

20050244436 Lawrence Livermore National Lab., Livermore, CA

USA High Energy Density Laboratory Astrophysics

Remington, B. A.; Nov. 30, 2004; 28 pp.; In English Report No.(s): DE2005-15011807; UCRL-CONF-208237; No Copyright; Avail.: National Technical Information Service (NTIS)

High-energy-density (HED) physics refers broadly to the study of macroscopic collections of matter under extreme conditions of temperature and density. The experimental facilities most widely used for these studies are high-power lasers and magnetic-pinch generators. The HED physics pursued on these facilities is still in its infancy, yet new regimes of experimental science are emerging. Examples from astrophysics include work relevant to planetary interiors, supernovae, astrophysical jets, and accreting compact objects (such as neutron stars and black holes). In this paper, we will review a selection of recent results in this new field of HED laboratory astrophysics and provide a brief look ahead to the coming decade. NTIS

Astrophysics; High Energy Interactions; Laboratory Astrophysics

20050244488 Lawrence Livermore National Lab., Livermore, CA USA

Chandra X-Ray Observations of WZ Sge Superoutburst

Weatley, P. J.; Mauche, C. W.; Oct. 25, 2004; 12 pp.; In English Report No.(s): DE2005-15014627; UCRL/PROC-20744; No Copyright; Avail.: Department of Energy Information Bridge

We present seven separate Chandra observations of the 2001 superoutburst of WZ Sge. The high-energy outburst was dominated by intense EUV emission lines, which we interpret as boundary layer emission scattered into our line of sight in an accretion disc wind. The direct boundary layer emission was hidden from view, presumably by the accretion disc. The optical outburst orbital hump was detected in the EUV, but the common superhump was not, indicating a geometric mechanism in the former and a dissipative mechanism in the latter. X-rays detected during outburst were not consistent with boundary layer emission and we argue that there must be a second source of X-rays in dwarf novae in outburst. NTIS

Dwarf Novae; X Ray Astrophysics Facility; X Rays

20050245037 Lawrence Livermore National Lab., Livermore, CA USA

Robust Extraction and Multi-Technique Analysis of Micrometeoroids Captured in Low Earth Orbit

Westphal, A. J.; Graham, G. A.; Bench, G.; Brennan, S.; Luening, K.; Apr. 20, 2004; 8 pp.; In English Report No.(s): DE2005-15014129; UCRL-CONF-203658; No Copyright; Avail.: National Technical Information Service (NTIS)

The use of low-density silica aerogel as the primary capture cell technology for the NASA Discovery mission Stardust to Comet Wild-2 is a strong motivation for researchers within the Meteoritics community to develop techniques to handle this material.

The unique properties of silica aerogel allow dust particles to be captured at hypervelocity speeds and to remain partially intact.

The same unique properties present difficulties in the preparation of particles for analysis.

Using tools borrowed from microbiologists, we have developed techniques for robustly extracting captured hypervelocity dust particles and their residues from aerogel collectors. NTIS

Aerogels; Extraction; Low Earth Orbits; Micrometeoroids

20050245157 Lawrence Livermore National Lab., Livermore, CA USA

Astrophysical and Astrochemical Insights into the Origin of Life

Ehrenfreund, P.; Becker, L.; Blank, J.; Brucato, J.; Apr. 30, 2002; 96 pp.; In English Report No.(s): DE2005-15013483; UCRL-ID-148252; No Copyright; Avail.: Department of Energy Information Bridge

Current experimental research investigating the origin of life is focused on the spontaneous formation of stable polymers out of monomers. However, understanding the spontaneous formation of structure is not enough to understand the formation of He. The introduction and evolution of information and complexity is essential to our definition of life. The formation of complexity and the means to distribute and store information is currently investigated in a number of theoretical frameworks; such as evolving algorithms, chaos theory, and modem evolution theory. In this article we review the physical and chemical processes that form and shape organic matter in space. In particular we discuss the chemical pathways of organic matter in the interstellar medium, their evolution in protoplanetary disks and their integration into solar system material. Furthermore we investigate the role of impacts and the delivery of organic matter to the prebiotic Earth. Processes that may have assembled prebiotic molecules to produce the first genetic material and ideas about the formation of complexity in chemical networks are discussed. NTIS

Astrophysics; Biological Evolution; Organic Materials; Polymers

20050245167 Lawrence Livermore National Lab., Livermore, CA USA, Arizona State Univ., Tempe, AZ USA, Hawaii Univ., Honolulu, HI, USA

Oxygen Isotopes in Refractory Inclusions from the Adelaide Carbonaceous Chondrite

Huss, G. R.; Hutcheon, I. D.; Krot, A. N.; Tachibana, S.; Nov. 03, 2003; 8 pp.; In English Report No.(s): DE2005-15013707; UCRL-PROC-200753; No Copyright; Avail.: National Technical Information Service (NTIS)

Except for the effects of terrestrial weathering on melilite, inclusions in Adelaide appear to retain the primary isotopic signatures acquired when they formed. Adelaide is thus an ideal meteorite for investigating processes that produced chondrules and CAIs. NTIS

Carbonaceous Chondrites; Inclusions; Oxygen Isotopes; Refractories

Source: NASA.