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Search indexed NASA NTRS and DOE OSTI research on propulsion, heat transfer, battery materials and energy systems. Follow report and document links to the original sources.

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At least 487 records · Page 27
All sourcesNASA NTRSDOE OSTI
NASA NTRS1993

30 Doradus - Ultraviolet and optical stellar photometry

Ultraviolet Imaging Telescope (UIT) UV magnitudes in four bands, together with optical B magnitudes, are presented for up to 314 early-type stars located in a 9.7 x 9.7 arcmin field centered on R136. The magnitudes have an rms uncertainty estimated at 0.10 mag from a comparison between the UIT magnitudes and the IUE spectra. Spectral types and E(B-V) color excesses are estimated. The mean color excesses following the two extinction curves agree well with the predictions of the two-component extinction model of Fitzpatrick and Savage (1984). However, the degree of nebular extinction is found to vary systematically by large amounts over the 30 Dor field. The minimum of nebular extinction in the central parts of the nebula suggests that dust has been expelled from this region by stellar winds. It is suggested that the form of the UV extinction curve can be understood as a consequence of the evolutionary state of the stellar population responsible for making the dust grains.

Hill, Jesse K.↗
NASA NTRS1994

Deep HST imaging of distant weak radio and field galaxies

We present deep Hubble Space Telescope (HST) Wide-Field Camera (WFC) V- and I-band images of three distant weak radio galaxies with z = 0.311-2.390 and seven field galaxies with z = 0.131-0.58. The images were deconvolved with both the Lucy and multiresolution CLEAN methods, which yield a restoring Full Width at Half Maximum (FWHM) of less than or equal to 0.2 sec, (nearly) preserve photons and signal-to-noise ratio at low spatial frequencies, and produce consistent light profiles down to our 2 sigma surface brightness sensitivity limit of V approximately 27.2 and I approximately 25.9 mag/sq arcsec. Multi-component image modeling was used to provide deconvolution-independent estimates of structural parameters for symmetric galaxies. We present 12-band (m(sub 2750) UBVRIgriJHK) photometry for a subset of the galaxies and bootstrap the unknown FOC/48 zero point at 2750 A in three independent ways (yielding m(sub 2750) = 21.34 +/- 0.09 mag for 1.0 e(-)/s). Two radio galaxies with z = 0.311 and 0.528, as well as one field galaxy with z = 0.58, have the colors and spectra of early-type galaxies, and a(exp 1/4)-like light profiles in the HST images. The two at z greater than 0.5 have little or no color gradients in V - I and are likely giant ellipticals, while the z = 0.311 radio galaxy has a dim exponential disk and is likely an S0. Six of the seven field galaxies have light profiles that indicate (small) inner bulges following a(exp 1/4) laws and outer exponential disks, both with little or no color gradients. These are (early-type) spiral galaxies with z = 0.131-0.528. About half have faint companions or bars. One shows lumpy structure, possibly a merger. The compact narrow-line galaxy 53W002 at z = 2.390 has less than or = 30% +/- 10% of its HST V and I flux in the central kiloparsec (due to its weak Active Galactic Nucleus (AGN)). Most of its light (V approximately equal to 23.3) occurs in a symmetric envelope with a regular a(exp 1/4)-like profile of effective radius a approximately equal to 1.1 sec (approximately equal to 12 kpc for H(sub 0) = 50, q(sub 0) = 0.1. Its (HST) V - I color varies at most from approximately 0.3 mag at a approximately equal to 0.2 sec to approximately 1.2 mag at a approximately greater than 0.4 sec, and possibly to approximately greater than 2.2 mag at a approximately greater than 1.2 sec. Together with its I - K color (approximately equal to 2.5 mag for a approximately greater than 1.0 sec-2.0 sec), this is consistent with an aging stellar population approximately 0.3-0.5 Gyr old in the galaxy center (a approx. less than 2 kpc radius), and possibly approximately 0.5-1.0 Gyr old at a approximately greater than 10 kpc radius. While its outer part may thus have started to collapse at z = 2.5-4, its inner part still is aligned with its redshifted Ly(alpha) cloud and its radio axis, possibly caused by star formation associated with the radio jet, or by reflection from its AGN cone.

Windhorst, R. A.↗
NASA NTRS1996

Research and Technology Highlights 1995

The mission of the NASA Langley Research Center is to increase the knowledge and capability of the United States in a full range of aeronautics disciplines and in selected space disciplines. This mission is accomplished by performing innovative research relevant to national needs and Agency goals, transferring technology to users in a timely manner, and providing development support to other United States Government agencies, industry, other NASA Centers, the educational community, and the local community. This report contains highlights of the major accomplishments and applications that have been made by Langley researchers and by our university and industry colleagues during the past year. The highlights illustrate both the broad range of research and technology (R&T) activities carried out by NASA Langley Research Center and the contributions of this work toward maintaining United States leadership in aeronautics and space research. An electronic version of the report is available at URL http://techreports.larc.nasa.gov/RandT95. This color version allows viewing, retrieving, and printing of the highlights, searching and browsing through the sections, and access to an on-line directory of Langley researchers.

Source record↗
NASA NTRS1995

Imaging System

The 1100C Virtual Window is based on technology developed under NASA Small Business Innovation (SBIR) contracts to Ames Research Center. For example, under one contract Dimension Technologies, Inc. developed a large autostereoscopic display for scientific visualization applications. The Virtual Window employs an innovative illumination system to deliver the depth and color of true 3D imaging. Its applications include surgery and Magnetic Resonance Imaging scans, viewing for teleoperated robots, training, and in aviation cockpit displays.

Source record↗
NASA NTRS2017

Rust Contamination from Water Leaks in the Cosmic Dust Lab and Lunar and Meteorite Thin Sections Labs at Johnson Space Center

On the early morning of September 15th, 2016, on the first floor of Building 31 at NASA-Johnson Space Center, the hose from a water chiller ruptured and began spraying water onto the floor. The water had been circulating though old metal pipes, and the leaked water contained rust-colored particulates. The water flooded much of the western wing of the building's ground floor before the leak was stopped, and it left behind a residue of rust across the floor, most notably in the Apollo and Meteorite Thin Section Labs and Sample Preparation Lab. No samples were damaged in the event, and the affected facilities are in the process of remediation. At the beginning of 2016, a separate leak occurred in the Cosmic Dust Lab, located in the same building. In that lab, a water leak occurred at the bottom of the sink used to clean the lab's tools and containers with ultra-pure water. Over years of use, the ultra-pure water eroded the metal sink piping and leaked water onto the inside of the lab's flow bench. This water also left behind a film of rusty material. The material was cleaned up and the metal piping was replaced with PVC pipe and sealed with Teflon plumber's tape. Samples of the rust detritus were collected from both incidents. These samples were imaged and analyzed to determine their chemical and mineralogical compositions. The purpose of these analyses is to document the nature of the detritus for future reference in the unlikely event that these materials occur as contaminants in the Cosmic Dust samples or Apollo or Meteorite thin sections.

Kent, J. J.↗
NASA NTRS1994

The stellar population in the core of M15

The inner core of the globular cluster M15 within approximately 2 sec of the geometrical center has been explored with high-resolution images taken through several broad-band UV filter with the Faint Object Camera (FOC) on board the Hubble Space Telescope (HST). Approximately 210 stars in this region down to a 5 sigma detection limit of m(sub 220) = 21.5 were reliably identified and located on a UV - U color magnitude diagram for the first time. A majority of stars (about 70% of the total) observed this way lie above the expected main-sequence turn-off of this cluster and below the sparsely populated horizontal branch. The extension of the main sequence above the turn-off separates this population in two roughly equal components situated to the right and left of this line. Most of the former must be classical blue stragglers while the rest belong to a new, as yet unidentified, population of very blue stars. Possibilities include, but are not restricted to, well-mixed single stars, subdwarfs, and helium white dwarfs. Similar objects are also found just outside the core out to approximately 6 sec from the center, but the brighter, presumably more massive ones, are sharply confined to the core itself. The measured excess of bright blue stars and the relative deficiency of bright red giants in the core are consistent with the blue inward color gradient measured from the ground and imply that dynamical evolution can significantly affect the stellar population in the very dense central regions of a high-concentration globular cluster like M15.

De Marchi, Guido↗
NASA NTRS1997

Visibility of wavelet quantization noise

The discrete wavelet transform (DWT) decomposes an image into bands that vary in spatial frequency and orientation. It is widely used for image compression. Measures of the visibility of DWT quantization errors are required to achieve optimal compression. Uniform quantization of a single band of coefficients results in an artifact that we call DWT uniform quantization noise; it is the sum of a lattice of random amplitude basis functions of the corresponding DWT synthesis filter. We measured visual detection thresholds for samples of DWT uniform quantization noise in Y, Cb, and Cr color channels. The spatial frequency of a wavelet is r 2-lambda, where r is display visual resolution in pixels/degree, and lambda is the wavelet level. Thresholds increase rapidly with wavelet spatial frequency. Thresholds also increase from Y to Cr to Cb, and with orientation from lowpass to horizontal/vertical to diagonal. We construct a mathematical model for DWT noise detection thresholds that is a function of level, orientation, and display visual resolution. This allows calculation of a "perceptually lossless" quantization matrix for which all errors are in theory below the visual threshold. The model may also be used as the basis for adaptive quantization schemes.

NASA Center ARC↗
DOE OSTI2024

Entanglement entropy of a color flux tube in (2+1)D Yang-Mills theory

We construct a novel flux tube entanglement entropy (FTE 2 ), defined as the excess entanglement entropy relative to the vacuum of a region of color flux stretching between a heavy quark-anti-quark pair in pure gauge Yang-Mills theory. We show that FTE 2 can be expressed in terms of correlators of Polyakov loops, is manifestly gauge-invariant, and therefore free of the ambiguities in computations of the entanglement entropy in gauge theories related to the choice of the center algebra. Employing the replica trick, we compute FTE 2 for SU(2) Yang-Mills theory in (2+1)D and demonstrate that it is finite in the continuum limit. We explore the properties of FTE 2 for a half-slab geometry, which allows us to vary the width and location of the slab, and the extent to which the slab cross-cuts the color flux tube. Following the intuition provided by computations of FTE 2 in (1+1)D, and in a thin string model, we examine the extent to which our FTE 2 results can be interpreted as the sum of an internal color entropy and a vibrational entropy corresponding to the transverse excitations of the string.

73 NUCLEAR PHYSICS AND RADIATION PHYSICS↗
NASA NTRS1973

Use of ERTS-1 pictures in coastal oceanography in British Columbia

The ERTS-1 color composite picture of the Vancouver-Victoria region illustrates the value of ERTS data for coastal oceanography. The water of the Fraser River plume which is so clearly visible in the center of the scene has been of interest to oceanographers on the west coast of Canada for a long time as an easily visible tracer of surface water circulation in the strait of Georgia. Maps of the plume at different states of the tide and with different river flow and weather were compiled from oblique aerial photographs in 1950 and used in the siting of sewage and other outfalls in the Vancouver area. More recently high level aerial photomosaics have been used to map the plume area, but the plume can spread over distances of 30 to 40 miles and many photographs, with the uneven illumination inherent in wide angle coverage, are needed for the mosaic. The ERTS satellite gives the first complete view of the plume area. Electronic enhancement of the images shows that the satellite's narrow angle coverage allows very weak surface turbidity features to be made visible to give information on surface currents over a wide area.

Gower, J. F. R.↗
NASA NTRS1984

Turbulent swirling combustion

The non-reacting flow produced by two confined, co- and/or counter-swirling jets wre measured by means of a two-color laser Doppler velocimeter. These results are compared with earlier experiments and with numerical predictions. It is shown that under both swirl conditions, a closed recirculation zone is created at the combustor center line. This zone is characterized by the presence of a one-cell toroidal vortex, low tangential velocities, high turbulent intensity, and large dissipation rates of the kinetic energy of turbulence.

Sommer, H. T.↗
NASA NTRS1985

Standard stars for cometary photometry

Interference filters centered at 0.365, 0.387, 0.406, 0.484, and 0.514 microns have been selected to represent UV continuum, CN emission, C3 emission, blue continuum, and C2 emission in cometary spectra, respectively. Adopted magnitudes and colors of this filter system are presented for 50 standard stars, ranging in bue magnitude from 4 to 12, in spectral type from O to K, and distributed primarily around equatorial regins of the sky. The tabulated uncertainties are generally of the order of 0.02 mag or smaller; the zero points of the photometric system are chosen so that blue continuum magnitudes are approximately equivalent to Johnson B, and so that color indices average zero for solar analog stars.

Wisniewski, W.↗
NASA NTRS2010

Galactic Bulge Giants: Probing Stellar and Galactic Evolution. 1. Catalogue of Spitzer IRAC and MIPS Sources (PREPRINT)

Aims. We aim at measuring mass-loss rates and the luminosities of a statistically large sample of Galactic bulge stars at several galactocentric radii. The sensitivity of previous infrared surveys of the bulge has been rather limited, thus fundamental questions for late stellar evolution, such as the stage at which substantial mass-loss begins on the red giant branch and its dependence on fundamental stellar properties, remain unanswered. We aim at providing evidence and answers to these questions. Methods. To this end, we observed seven 15 15 arcmin2 fields in the nuclear bulge and its vicinity with unprecedented sensitivity using the IRAC and MIPS imaging instruments on-board the Spitzer Space Telescope. In each of the fields, tens of thousands of point sources were detected. Results. In the first paper based on this data set, we present the observations, data reduction, the final catalogue of sources, and a detailed comparison to previous mid-IR surveys of the Galactic bulge, as well as to theoretical isochrones. We find in general good agreement with other surveys and the isochrones, supporting the high quality of our catalogue.

CMD(COLOR MAGNITUDE DIAGRAMS)↗
NASA NTRS1996

Color Image Processing and Object Tracking System

This report describes a personal computer based system for automatic and semiautomatic tracking of objects on film or video tape, developed to meet the needs of the Microgravity Combustion and Fluids Science Research Programs at the NASA Lewis Research Center. The system consists of individual hardware components working under computer control to achieve a high degree of automation. The most important hardware components include 16-mm and 35-mm film transports, a high resolution digital camera mounted on a x-y-z micro-positioning stage, an S-VHS tapedeck, an Hi8 tapedeck, video laserdisk, and a framegrabber. All of the image input devices are remotely controlled by a computer. Software was developed to integrate the overall operation of the system including device frame incrementation, grabbing of image frames, image processing of the object's neighborhood, locating the position of the object being tracked, and storing the coordinates in a file. This process is performed repeatedly until the last frame is reached. Several different tracking methods are supported. To illustrate the process, two representative applications of the system are described. These applications represent typical uses of the system and include tracking the propagation of a flame front and tracking the movement of a liquid-gas interface with extremely poor visibility.

Klimek, Robert B.↗
NASA NTRS2000

Interstellar Extinction in the Vicinity of the Galactic Center

We present J (1.2 microns), H (1-6 microns), K' (2.11 microns) and Br(gamma) (2.166 microns) images from four large regions within the central 40 pc of the Galaxy. Localized variations in the extinction, as determined by observations of the stellar population, are examined using the median H-K' color as a function of position within each region. As the value of the derived extinction from the stars is dependent upon the intrinsic magnitude of the assumed stellar type, the J-H vs. H-K' diagrams are first used to investigate the distribution of stellar types in the four regions. We find that there is a distinct OB population, contrary to earlier assumptions, with the ratio of K and M giants and supergiants to OB stars approximately twice that of the solar neighborhood. Although the on the scale of approx. l' fluctuations in the extinction are on the order of A(sub V) approx. 2, throughout the entire region the extinction varies from A(sub V) approx. greater than 25 to A(sub V) approx. less than 40. We also examine whether there is any variation in the extinction and stellar number density relative to the usual radio features in these regions and do not find a significant correlation. Spectral imaging in Br(gamma) 2.166 microns emission shows a strong morphological correspondence between the 6 cm radio images and the diffuse Br(gamma) emission. By comparing the theoretical Br(gamma) flux derived from the radio flux using recombination theory, with our measured Br(gamma) flux, we obtain a second, independent, estimate of the extinction. We compare the two data sets and find that the extinction as derived from the stars is consistently greater, sometimes by a factor of two, than the value of the extinction derived from the Br(gamma) images. The derived extinction in various regions, however, is insufficient for any of these regions-to be located behind the molecular clouds as previously observed in the Galactic Center, consistent with the theory that the observed radio emission is produced on the foreground surface of these clouds.

Cotera, Angela S.↗
NASA NTRS1998

Interstellar Extinction in the Vicinity of the Galactic Center

We present J (1.2 microns) H (1-6 microns) K' (2.11 microns) and Br(gamma) (2.166 microns) images from four large regions within the central 40 pc of the Galaxy. Localized variations in the extinction, as determined by observations of the stellar population, are examined using the median H-K' color as a function of position within each region. As the value of the derived extinction from the stars is dependent upon the intrinsic magnitude of the assumed stellar type, the J-H vs. H-K' diagrams are first used to investigate the distribution of stellar types in the four regions. We find that there is a distinct OB population, contrary to earlier assumptions, with the ratio of K and M giants and supergiants to OB stars approximately twice that of the solar neighborhood. Although the on the scale of approx. 1 min. fluctuations in the extinction are on the order of A(sub V) approx. greater than 2, throughout the entire region the extinction varies from A(sub V) approx. greater than 25 to A(sub V) approx. less than 40. We also examine whether there is any variation in the extinction and stellar number density relative to the unusual radio features in these regions and do not find a significant correlation. Spectral imaging in Br(gamma) 2.166 microns emission shows a strong morphological correspondence between the 6 cm radio images and the diffuse Br(gamma) emission. By comparing the theoretical Br(gamma) flux derived from the radio flux using recombination theory, with our measured Br(gamma) flux, we obtain a second, independent, estimate of the extinction. We compare the two data sets and find that the extinction as derived from the stars is consistently greater, sometimes by a factor of two, than the value of the extinction derived from the Br(gamma) images. The derived extinction in various regions, however, is insufficient for any of these regions to be located behind the molecular clouds as previously observed in the Galactic Center, consistent with the theory that the observed radio emission is produced on the foreground surface of these clouds.

Cotera, Angela S.↗
NASA NTRS2009

Further Studies on the Physical and Biogeochemical Causes for Large Interannual Changes in the Patagonian Shelf Spring-Summer Phytoplankton Bloom Biomass

A very strong and persistent phytoplankton bloom was observed by ocean color satellites during September - December 2003 along the northern Patagonian shelf. The 2003 bloom had the highest extent and chlorophyll a (Chl-a) concentrations of the entire Sea-viewing Wide Field-of-view Sensor (SeaWiFS) period (1997 to present). SeaWiFS-derived Chl-a exceeded 20 mg/cu m in November at the bloom center. The bloom was most extensive in December when it spanned more than 300 km across the shelf and nearly 900 km north-south (35degS to 43degS). The northward reach and the deep penetration on the shelf of the 2003 bloom were quite anomalous when compared with other years, which showed the bloom more confined to the Patagonian shelf break (PSB). The PSB bloom is a conspicuous austral spring-summer feature detected by ocean color satellites and its timing can be explained using the Sverdrup critical depth theory. Based on high-resolution numerical simulations, in situ and remote sensing data, we provide some suggestions for the probable mechanisms responsible for that large interannual change of biomass as seen by ocean color satellites. Potential sources of macro and micro (e.g., Fe) nutrients that sustain the high phytoplankton productivity of the Patagonian shelf waters are identified, and the most likely physical processes that maintain the nutrient balance in the region are discussed.

Signorini, Sergio R.↗
NASA NTRS1982

Stellar populations in the edge-on spiral galaxy NGC 4565. I - Surface brightness and color distributions

Results are presented for photographic and photoelectric photometry of the edge-on Sb galaxy NGC 4565. Major-axis, minor-axis, and perpendicular surface brightness profiles are determined, along with color gradients parallel and perpendicular to the plane of the galaxy. It is found that the galaxy's light can be deconvolved naturally into five components: (1) a starlike nucleus located at the center of the bulge and the edge of the dust lane; (2) a thin disk containing the gas and dust, the young OB stars, and the spiral arms; (3) a thick disk that may be a locally isothermal sheet of old Population I metal-rich stars; (4) a bulge that merges smoothly into the thick disk at a radial distance of about 2.9 kpc; and (5) a corona whose light dominates the perpendicular profiles from about 2.9 to at least 8.2 kpc above the galactic plane.

Jensen, E. B.↗