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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 55 records · Page 3
All sourcesNASA NTRSDOE OSTI
NASA NTRS1986

A Search for Metal Lines in the Spectra of DA White Dwarfs

A theoretical analysis was carried out in order to interpret the ultraviolet spectra of DB white dwarfs obtained earlier with the International Ultraviolet Explorer (IUE) satellite. Here the results of the IUE ultraviolet spectroscopy combined with visual data and model atmospheres of DB white dwarfs are reported. In particular, a search for spectra lines due to the element carbon using the ultraviolet was made. In no case is there a positive detection of carbon and from these data, and upper limits for carbon by number relative to helium are derived in the range of C: He 10 to the minus 5 power to 10 to the minus 7 power for the 16 DB stars with ultraviolet spectra in the temperature range 11400 K T sub EFF less than 2300 K. The low carbon abundances found in the atmospheres of the DB stars agree well with the hypothesis that the atmospheric carbon observed in the cooler DQ members of the helium-rich white dwarf sequence is produced by a convective dredging mechanism.

Wegner, G. A.↗
NASA NTRS1992

Search for spectral lines in cosmic gamma-ray bursts

Time-integrated spectra from 177 gamma-ray bursts observed by the Gamma Ray Spectrometer (GRS) on NASA's Solar Maximum Mission satellite (SMM) have been systematically searched for evidence of emission lines in the range 300 keV and higher. The distribution of fitted line strengths is consistent with what is expected from a random sample of data, suggesting that there are no statistically significant narrow or moderately broadened line features in any of the bursts.

Messina, Daniel C.↗
NASA NTRS1972

Search for coronal line emission from the Cygnus Loop.

The flux from the edges of the Cygnus Loop in the forbidden Fe XIV coronal line at 5303 A is measured to be less than 5 nanoergs per sq cm per sterad per sec (0.017 R) in a 3 A band centered on the line. This upper limit is an order of magnitude lower than the predicted total flux in the line and implies that there must be substantial broadening of the line profile by mass motion or that the temperature is somewhat higher than the present best estimate from X-ray data.

Kurtz, D. W.↗
NASA NTRS1982

A search for UV line variability in R136a

The brightest object in the central cluster of stars in the 30 Doradus nebula is R136a. Optical imaging and ultraviolet spectroscopy show that a luminosity originates in a volume less than 0.1 pc across. A very tight cluster of approximately 30 luminous O and WR stars produces this energy. An alternative interpretation is the possibility that a single supermassive object dominates the light. The visual spectrum is classified as WN 4.5. A common characteristic of WN spectra is variability of the emission lines, especially He II lambda 4686.

Ebbets, D. C.↗
NASA NTRS1984

Search for emission lines in the gaseous halo of edge-on galaxies

Careful reductions of the short wave prime camera (SWP) spectrum was carried out. A line by line inspection of the spectrum was used to eliminate spurious spikes and a median filter applied to eliminate high frequency noise. Upper limits were obtained for far ultraviolet emission from a hot galactic halo.

Bixler, J.↗
NASA NTRS1992

Search for infrared absorption lines of atmospheric chlorine monoxide (ClO)

A search for features of the ClO (1-0) vibration-rotation band has been conducted based on a 5000 signal-to-rms noise ratio IR spectrum derived by coadding 39 high-quality 0.0053/cm resolution solar spectra recorded with the McMath Fourier transform spectrometer on Kitt Peak. Evidence for absorption has been found at the locations of several of the stronger ClO P-branch lines with minimal interference. Detailed results are presented for the P(8.5) and P(7.5) 2Pi3/2-2Pi3/2 lines of Cl-35O at 833.2974 and 834.6249/cm, respectively. If ClO is present in the stratosphere at the concentrations indicated by other methods, our analysis indicates that modest improvements in signal-to-noise ratio and spectral resolution would permit a definitive detection of ClO in IR ground-based spectra.

Rinsland, Curtis P.↗
DOE OSTI2026

Early results in the search for extreme coronal line emitters with the Dark Energy Spectroscopic Instrument

Here, we present the results of our search through the early data release (EDR) of the Dark Energy Spectroscopic Instrument (DESI) for extreme coronal line emitters (ECLEs) – a rare classification of galaxies displaying strong, high-ionization iron coronal emission lines within their spectra. With the requirement of a strong X-ray continuum to generate the coronal emission, ECLEs have been linked to both active galactic nuclei (AGNs) and tidal disruption events (TDEs). We focus our search on identifying TDE-linked ECLEs. We identify three such objects within the EDR sample, highlighting DESI’s effectiveness for discovering new nuclear transients, and determine a galaxy-normalized TDE-linked ECLE rate of RG=5 −3+5×10−6 galaxy−1 yr−1 at a median redshift of z=0.2 – broadly consistent with previous work. Additionally, we identify more than 200 AGNs displaying coronal emission lines, which serve as the primary astrophysical contaminants in searches for TDE-related events. We also include an outline of the custom python code developed for this search.

Clark, Peter [Southampton U.; Portsmouth U., ICG] ↗
NASA NTRS2007

AIRSAR Web-Based Data Processing

The AIRSAR automated, Web-based data processing and distribution system is an integrated, end-to-end synthetic aperture radar (SAR) processing system. Designed to function under limited resources and rigorous demands, AIRSAR eliminates operational errors and provides for paperless archiving. Also, it provides a yearly tune-up of the processor on flight missions, as well as quality assurance with new radar modes and anomalous data compensation. The software fully integrates a Web-based SAR data-user request subsystem, a data processing system to automatically generate co-registered multi-frequency images from both polarimetric and interferometric data collection modes in 80/40/20 MHz bandwidth, an automated verification quality assurance subsystem, and an automatic data distribution system for use in the remote-sensor community. Features include Survey Automation Processing in which the software can automatically generate a quick-look image from an entire 90-GB SAR raw data 32-MB/s tape overnight without operator intervention. Also, the software allows product ordering and distribution via a Web-based user request system. To make AIRSAR more user friendly, it has been designed to let users search by entering the desired mission flight line (Missions Searching), or to search for any mission flight line by entering the desired latitude and longitude (Map Searching). For precision image automation processing, the software generates the products according to each data processing request stored in the database via a Queue management system. Users are able to have automatic generation of coregistered multi-frequency images as the software generates polarimetric and/or interferometric SAR data processing in ground and/or slant projection according to user processing requests for one of the 12 radar modes.

Chu, Anhua↗
NASA NTRS1974

Search for gamma ray lines from supernovae and supernova remnants

A gamma ray monitor with a NaI crystal shielded with a cup-shaped CsI cover was contained in the rotating wheel compartment of the OSO-7 spacecraft for measuring the gamma ray spectra from 0.3 to 10 MeV in search for gamma ray lines from a possible remnant in the Gum Nebula and the apparent Type I supernovae in NGC5253. A brief analysis of data yielded no positive indications for X-rays, gamma ray lines, or continuum from these sources.

Chupp, E. L.↗
NASA NTRS1981

Search for optical coronal line emission from the X-ray sources Epsilon Orionis /B0 Ia/ and Kappa Orionis /B0.5 Ia/

A search was conducted for evidence of a coronal region at the base of the winds of Epsilon Ori and Kappa Ori, by means of high signal-to-noise observations at the forbidden lines of Fe X, at 6574 A, and Fe XIV, 5303 A. Both stars have been detected as soft X-ray sources, and show anomalously strong O VI lines in their UV spectra. Large coronal emission measures were expected from the total X-ray flux and Auger-enhanced ionization, but the fact that the iron coronal lines were not detected places new limits on the emission measure if the total temperature is in the range of 700,000-3,000,000 or more than 1,000,000 for Kappa Ori and 2,000,000 for Epsilon Ori. It is suggested that at least some of the X-rays arise, not from the base corona, but from source features farther out in the wind.

Nordsieck, K. H.↗
NASA NTRS1987

New lines of ethylene and a search for methylene in IRC + 10216

Seven new lines in the 10 micron nu7 band of C2H4 have been detected in the highly obscured carbon star IRC + 10216. The line intensities cannot be well described by a single rotational temperature, in contrast to the lines of CH4 and SiH4 previously observed in this source. There are at least three interpretations: the line intensities are variable on a time scale of months and years, C2H4 lines are formed over a region less homogeneous than that of CH4 and SiH4, or ethylene is somewhat nonthermally excited. Regardless, the line intensities indicate an average rotational temperature of 100 K and a column density of about 4 x 10 to the 15th/sq cm, which is approximately 2 x 10 to the -5th times the CO abundance. A search was also made for infrared transitions of CH2, the methylene radical. No lines were detected, but the observational limits are compared with the abundance and radial distribution for CH2 predicted by a model invoking the photodissociation of CH4.

Goldhaber, D. M.↗
NASA NTRS1978

Ultraviolet observations of cool stars. VI - L alpha and Mg II emission line profiles /and a search for flux variability/ in Arcturus

High-precision, high-resolution profiles of the L alpha and Mg II k chromospheric emission lines from Arcturus (alpha Boo) obtained with the Princeton Experimental Package aboard the Copernicus satellite are presented. Asymmetries seen in the profiles of these lines are probably intrinsic to the star, rather than the result of interstellar absorption. In contrast to previous observations of the Ca II K emission line, no evidence is found during a three-year period for variability in the profiles or in the total fluxes from these lines on time scales ranging from hours to months. Also presented is a flux profile of the O I 1302 line and flux upper limits for L beta, O VI 1032, Si III 1206, and O V 1218.

Mcclintock, W.↗
NASA NTRS2018

Optical Polarisation Variability of Radio-Loud Narrow-Line Seyfert 1 Galaxies: Search for Long Rotations of the Polarisation Plane

This work describes multi-site optical polarimetric observations of several radio-loud Narrow Line Seyfert 1 galaxies. This source class, and the sources in this study, were discovered to be detectable at gamma-ray energies by the Large Area Telescope (LAT) aboard the Fermi satellite. GSFC has played a key role in the development, launch, and operation of Fermi/LAT.

Angelakis, E.↗
NASA NTRS1984

The 12 micron band of ethane - High-resolution laboratory analysis with candidate lines for infrared heterodyne searches

Attention is given to the results of a laboratory study of the v9 band of ethane at 12 microns, using both high resolution Fourier transform and diode laser absorption spectroscopy. The analysis to which about 2000 transitions in this band have been subjected includes the normal rotational terms as well as the higher order effects of l-doubling, l-resonance, internal rotation, and a Coriolis resonance with the 3v4 state. A model is presented for the v9 band which is able to reproduce the observed features to an accuracy of better than 0.001/cm, and a list has been compiled for v9 transitions, occurring near C-14O2 laser lines, that are good candidates for laser heterodyne searches.

Atakan, A. K.↗
NASA NTRS1978

Search for broad gamma ray lines with the UCR double Compton scatter telescope

The operation of a double scatter telescope and the evaluation of data obtained during a 24 hour balloon flight are discussed. An increase in gamma rays was observed as the galactic anti-center crossed the aperature of the telescope. Searches for lines from p(n,gamma)d at 2.2 MeV, C-12* at 4.4 MeV and on -16* at 6.1 MeV and for other lines broadened or redshifted are being conducted to identify the processes responsible for the production of celestial gamma rays. Two upper limits for lines in the angalactic anti-center direction at 4.4 MeV and 6.1 MeV are 6 and 4 x 10 to the minus 4 power gamma/sq cm-s.

White, R. S.↗
NASA NTRS1994

SMM observations of gamma-ray transients. 2: A search for gamma-ray lines between 400 and 600 keV from the Crab Nebula

We have search spectra obtained by the Solar Maximum Mission Gamma-Ray Spectrometer during 1981-1988 for evidence of transient gamma-ray lines from the Crab Nebula which have been reported by previous experiments at energies 400-460 keV and 539 keV. We find no evidence for significant emission in any of these lines on time scales between aproximately 1 day and approximately 1 yr. Our 3 sigma upper limits on the transient flux during 1 d intervals are approximately equal to 2.2 x 10(exp -3) photons/sq cm/s for narrow lines at any energy, and approximately equal to 2.9 x 10(exp -3) photons/sq cm/s for the 539 keV line if it is as broad as 42 keV Full Width at Half Maximum (FWHM). We also searched our data during the approximately 5 hr period on 1981 June 6 during which Owens, Myers, & Thompson (1985) reported a strong line at 405 keV. We detected no line down to a 3 upper sigma limit of 3.3 x 10(exp -3) photons/sq cm/s in disagreement with the flux 7.2 +/- 2.1 x 10(exp -3) photos/sq cm/s measured by Owens et al.

Harris, Michael J.↗
NASA NTRS2013

Moduli Dark Matter and the Search for Its Decay Line using Suzaku X-Ray Telescope

Light scalar fields called moduli arise from a variety of different models involving supersymmetry and/or string theory; thus their existence is a generic prediction of leading theories for physics beyond the standard model. They also present a formidable, long-standing problem for cosmology. We argue that an anthropic solution to the moduli problem exists in the case of small moduli masses and that it automatically leads to dark matter in the form of moduli. The recent discovery of the 125 GeV Higgs boson implies a lower bound on the moduli mass of about a keV. This form of dark matter is consistent with the observed properties of structure formation, and it is amenable to detection with the help of x-ray telescopes. We present the results of a search for such dark matter particles using spectra extracted from the first deep x-ray observations of the Draco and Ursa Minor dwarf spheroidal galaxies, which are darkmatter- dominated systems with extreme mass-to-light ratios and low intrinsic backgrounds. No emission line is positively detected, and we set new constraints on the relevant new physics.

Kusenko, Alexander↗